Hypnotherapy is a type of mind-body intervention in which hypnosis
is used to create a state of focused attention and increased
suggestibility in the treatment of a medical or psychological disorder
or concern.
"Induces
hypnotic state in client to increase motivation or alter behavior
patterns: Consults with client to determine nature of problem. Prepares
client to enter hypnotic state by explaining how hypnosis works and what
client will experience. Tests subject to determine degree of physical
and emotional suggestibility. Induces hypnotic state in client, using
individualized methods and techniques of hypnosis based on
interpretation of test results and analysis of client's problem. May
train client in self-hypnosis conditioning."
In the 1950s, Milton H. Erickson
developed a radically different approach to hypnotism, which has
subsequently become known as "Ericksonian hypnotherapy" or
"Neo-Ericksonian hypnotherapy." Based on his belief that dysfunctional
behaviors were defined by social tension, Erickson coopted the subject's
behavior to establish rapport, a strategy he termed "utilization." Once
rapport was established, he made use of an informal conversational
approach to direct awareness. His methods included complex language
patterns and client-specific therapeutic strategies (reflecting the
nature of utilization). He claimed to have developed ways to suggest
behavior changes during apparently ordinary conversation.
This divergence from tradition led some, including Andre Weitzenhoffer, to dispute whether Erickson was right to label his approach "hypnosis" at all.
Erickson's foundational paper, however, considers hypnosis as a mental
state in which specific types of "work" may be done, rather than a
technique of induction.
The founders of neuro-linguistic programming
(NLP), a method somewhat similar in some regards to some versions of
hypnotherapy, claimed that they had modelled the work of Erickson
extensively and assimilated it into their approach. Weitzenhoffer disputed whether NLP bears any genuine resemblance to Erickson's work.
Solution-focused hypnotherapy
In the 2000s, hypnotherapists began to combine aspects of solution-focused brief therapy
(SFBT) with Ericksonian hypnotherapy to produce therapy that was
goal-focused (what the client wanted to achieve) rather than the more
traditional problem-focused approach (spending time discussing the
issues that brought the client to seek help). A solution-focused
hypnotherapy session may include techniques from NLP.
Cognitive/behavioral hypnotherapy
Cognitive behavioral hypnotherapy (CBH) is an integrated psychological therapy employing clinical hypnosis and cognitive behavioral therapy (CBT).
The use of CBT in conjunction with hypnotherapy may result in greater
treatment effectiveness. A meta-analysis of eight different researches
revealed "a 70% greater improvement" for patients undergoing an
integrated treatment to those using CBT only.
In 1974, Theodore X. Barber and his colleagues published a review of the research which argued, following the earlier social psychology of Theodore R. Sarbin,
that hypnotism was better understood not as a "special state" but as
the result of normal psychological variables, such as active
imagination, expectation, appropriate attitudes, and motivation.
Barber introduced the term "cognitive-behavioral" to describe the
nonstate theory of hypnotism, and discussed its application to behavior
therapy.
The growing application of cognitive and behavioral psychological
theories and concepts to the explanation of hypnosis paved the way for a
closer integration of hypnotherapy with various cognitive and
behavioral therapies.
Many cognitive and behavioral therapies were themselves originally influenced by older hypnotherapy techniques, e.g., the systematic desensitisation of Joseph Wolpe, the cardinal technique of early behavior therapy, was originally called "hypnotic desensitisation" and derived from the Medical Hypnosis (1948) of Lewis Wolberg.
Curative hypnotherapy
Dr. Peter Marshall, author of A Handbook of Hypnotherapy,
devised the Trance Theory of Mental Illness, which asserts that people
suffering from depression, or certain other kinds of neuroses, are
already living in a trance. He asserts that this means the
hypnotherapist does not need to induce trance, but instead to make them
understand this and lead them out of it.
Mindful hypnotherapy
Mindful hypnotherapy is therapy that incorporates mindfulness and hypnotherapy. A pilot study was made at Baylor University, Texas, and published in the International Journal of Clinical and Experimental Hypnosis.
Dr. Gary Elkins, director of the Mind-Body Medicine Research Laboratory
at Baylor University called it "a valuable option for treating anxiety
and stress reduction” and "an innovative mind-body therapy". The study
showed a decrease in stress and an increase in mindfulness.
Relationship to scientific medicine
Hypnotherapy
practitioners occasionally attract the attention of mainstream
medicine. Attempts to instill academic rigor have been frustrated by the
complexity of client suggestibility, which has social and cultural
aspects, including the reputation of the practitioner. Results achieved
in one time and center of study have not been reliably transmitted to
future generations.
In the 1700s Anton Mesmer offered pseudoscientific justification for his practices, but his rationalizations were debunked by a commission that included Benjamin Franklin.
Uses
Clinicians
choose hypnotherapy to address a wide range of circumstances; however,
according to Yeates (2016), people choose to have hypnotherapy for many
other reasons:
"Ignoring specific issues such as performance anxiety,
road rage, weight, smoking, drinking, unsafe sex, etc., those seeking
hypnotherapy today do so because of ill-defined, vague feelings that:
(a) their health is far from optimal;
(b) their worry about past/present/future events is excessive and debilitating;
(c) they are not comfortable with who they are;
(d) they’re not performing up to the level of their true potential; and/or
(e) their lives are lacking some significant (but unidentified) thing."
Menopause
There is evidence supporting the use of hypnotherapy in the treatment of menopause related symptoms, including hot flashes. The North American Menopause Society recommends hypnotherapy for the nonhormonal management of menopause-associated vasomotor symptoms, giving it the highest level of evidence.
Irritable bowel syndrome
The use of hypnotherapy in treating the symptoms of irritable bowel syndrome is supported by research, including randomized controlled trials.
A 2015 audit of 1000 patients undertaking gut-focused hypnotherapy in
normal clinical practice found that hypnotherapy was an effective
intervention for refractory IBS. Gut-directed hypnotherapy is recommended in the treatment of irritable bowel syndrome by the American College of Gastroenterology clinical guideline for the management of IBS.
Childbirth
Hypnotherapy is often applied in the birthing process and the post-natal period, but there is insufficient evidence to determine if it alleviates pain during childbirth and no evidence that it is effective against post-natal depression.
Until 2012, there was no thorough research on this topic. However, in
2013 the study was conducted during which it was found that: “The use of
hypnosis in childbirth leads to a decrease in the amount of
pharmacological analgesia and oxytocin used, which reduces the duration
of the first stage of labor”.
In 2013, studies were conducted in Denmark, during which it was
concluded that "The self-hypnosis course improves the experience of
childbirth in women and also reduces the level of fear".
In 2015, a similar study was conducted in the UK by a group of
researchers: "The positive experience of self-hypnosis gives a sense of
calm, confidence and empowerment in childbirth". Hypnobirthing has been used by stars such as Kate Middleton.
Bulimia
Literature shows that a wide variety of hypnotic interventions have been investigated for the treatment of bulimia nervosa, with inconclusive effect.
Similar studies have shown that groups suffering from bulimia nervosa,
undergoing hypnotherapy, were more exceptional to no treatment,
placebos, or other alternative treatments.
Other uses
Among its many other applications in other medical domains, hypnotism was used therapeutically, by some alienists in the Victorian era, to treat the condition then known as hysteria.
Modern hypnotherapy is widely accepted for the treatment of certain habit disorders, to control irrational fears, as well as in the treatment of conditions such as insomnia and addiction. Hypnosis has also been used to enhance recovery from non-psychological conditions such as after surgical procedures, in breast cancer care and even with gastro-intestinal problems.
Efficacy
A
2003 meta-analysis on the efficacy of hypnotherapy concluded that "the
efficacy of hypnosis is not verified for a considerable part of the
spectrum of psychotherapeutic practice."
In 2005, a meta-analysis by the Cochrane Collaboration
found no evidence that hypnotherapy was more successful than other
treatments or no treatment in achieving cessation of smoking for at
least six months.
In 2007, a meta-analysis from the Cochrane Collaboration found that
the therapeutic effect of hypnotherapy was "superior to that of a
waiting list control or usual medical management, for abdominal pain and
composite primary IBS symptoms, in the short term in patients who fail
standard medical therapy", with no harmful side-effects. However the
authors noted that the quality of data available was inadequate to draw
any firm conclusions.
Two Cochrane reviews in 2012 concluded that there was insufficient
evidence to support its efficacy in managing the pain of childbirth or post-natal depression.
In 2016, a literature review published in La Presse Médicale found that there is not sufficient evidence to "support the efficacy of hypnosis in chronic anxiety disorders".
In 2019, a Cochrane review was unable to find evidence of benefit of
hypnosis in smoking cessation, and suggested if there is, it is small
at best.
A 2019 meta-analysis of hypnosis as a treatment for anxiety found
that "the average participant receiving hypnosis reduced anxiety more
than about 79% of control participants," also noting that "hypnosis was
more effective in reducing anxiety when combined with other
psychological interventions than when used as a stand-alone treatment."
Occupational accreditation
United States
The
laws regarding hypnosis and hypnotherapy vary by state and
municipality. Some states, like Colorado, Connecticut and Washington,
have mandatory licensing and registration requirements, while many other
states have no specific regulations governing the practice of
hypnotherapy.
UK Confederation of Hypnotherapy Organisations (UKCHO)
The regulation of the hypnotherapy profession in the UK is at present the main focus of UKCHO,
a non-profit umbrella body for hypnotherapy organisations. Founded in
1998 to provide a non-political arena to discuss and implement changes
to the profession of hypnotherapy, UKCHO currently represents 9 of the
UK's professional hypnotherapy organisations and has developed standards
of training for hypnotherapists, along with codes of conduct and
practice that all UKCHO registered hypnotherapists are governed by. As a
step towards the regulation of the profession, UKCHO's website now
includes a National Public Register of Hypnotherapists
who have been registered by UKCHO's Member Organisations and are
therefore subject to UKCHO's professional standards. Further steps to
full regulation of the hypnotherapy profession will be taken in
consultation with the Prince's Foundation for Integrated Health.
The National Council for Hypnotherapy (NCH)
The
National Council for Hypnotherapy is a Professional Association,
established in 1973 to create a National Membership Organisation for
independent Hypnotherapy Practitioners.
Australia
Professional hypnotherapy and use of the occupational titles hypnotherapist or clinical hypnotherapist are not government-regulated in Australia.
In 1996, as a result of a three-year research project led by Lindsay B. Yeates, the Australian Hypnotherapists Association
(founded in 1949), the oldest hypnotism-oriented professional
organization in Australia, instituted a peer-group accreditation system
for full-time Australian professional hypnotherapists, the first of its
kind in the world, which "accredit[ed] specific individuals on the basis
of their actual demonstrated knowledge and clinical performance;
instead of approving particular 'courses' or approving particular
'teaching institutions'" (Yeates, 1996, p.iv; 1999, p.xiv). The system was further revised in 1999.
Australian hypnotism/hypnotherapy organizations (including the
Australian Hypnotherapists Association) are seeking government
regulation similar to other mental health professions. However,
currently hypnotherapy is not subject to government regulation through
the Australian Health Practitioner Regulation Agency (AHPRA).
Traditional ecological knowledge (TEK) describes indigenous and other traditional knowledge of local resources. As a field of study in Northern American
anthropology, TEK refers to "a cumulative body of knowledge, belief,
and practice, evolving by accumulation of TEK and handed down through
generations through traditional songs, stories and beliefs. It is
concerned with the relationship of living beings (including human) with
their traditional groups and with their environment."
It is important to note that indigenous knowledge is not a universal
concept among various societies, but is referred to a system of
knowledge traditions or practices that are heavily dependent on "place". Such knowledge is used in natural resource management as a substitute for baseline environmental data in cases where there is little recorded scientific data, or may complement Western scientific methods of ecological management.
The application of TEK in the field of ecological management and
science is still controversial, as methods of acquiring and collecting
knowledge—although often including forms of empirical research and experimentation—differ from those used to create and validatescientific ecological knowledge from a Western perspective. Non-tribal government agencies, such as the U.S. EPA,
have established integration programs with some tribal governments in
order to incorporate TEK in environmental plans and climate change
tracking.
There is a debate whether Indigenous populations retain an intellectual property right over traditional knowledge and whether use of this knowledge requires prior permission and license. This is especially complicated because TEK is most frequently preserved as oral tradition and as such may lack objectively confirmed documentation.
As such, the same methods that could resolve the issue of documentation
to meet Western requirements may compromise the very nature of
traditional knowledge.
Traditional knowledge is used to maintain resources necessary for survival. While TEK itself, and the communities tied to the oral tradition, may become threatened in the context of rapid climate change or environmental degradation, TEK is proving critical for understanding the impacts of those changes within the ecosystem.
TEK can also refer to traditional environmental knowledge which emphasizes the different components and interactions of the environment.
Development of the field
The earliest systematic studies of TEK were conducted in
anthropology. Ecological knowledge was studied through the lens of
ethnoecology, "an approach that focuses on the conceptions of ecological
relationships held by a people or a culture," in understanding how
systems of knowledge were developed by a given culture. Harold Colyer Conklin, an American anthropologist who pioneered the study of ethnoscience,
took the lead in documenting indigenous ways of understanding the
natural world. Conklin and others documented how traditional peoples,
such as Philippine horticulturists, displayed remarkable and
exceptionally detailed knowledge about the natural history of places
where they resided. Direct involvement in gathering, fashioning products
from, and using local plants and animals created a scheme in which the
biological world and the cultural world were tightly intertwined.
Although the field of TEK began with documentation of lists of species
used by different indigenous groups and their "taxonomies of plants,
animals, and later, of other environmental features such as soils," the
shift from documentation to consideration of functional relationships
and mechanisms gave rise to the field as it is recognized today. In
emphasizing the study of adaptive processes, which argues that social
organization itself is an ecological adaptational response by a group to
its local environment, human-nature relations and the practical
techniques on which these relationships and culture depended, the field
of TEK could analyze a broad range of questions related to cultural ecology and ecological anthropology.
By the mid-1980s a growing body of literature on traditional
ecological knowledge documented both the environmental knowledge held by
diverse indigenous peoples and their ecological relations.
The studies included examining "cultivation and biodiversity
conservation in tropical ecosystems, and traditional knowledge and
management systems in coastal fisheries and lagoons, semi-arid areas,
and the Arctic." What these studies illustrated was that a variety of
"traditional peoples had their own understandings of ecological
relationships and distinct traditions of resource management."
The rise of traditional ecological knowledge at this time led to
international recognition of its potential applications in resource
management practices and sustainable development. The 1987 report by the
World Commission on Environment and Development reflects the consensus
at the time. The report points out that the successes of the 20th
century (decreases in infant mortality, increases in life expectancy,
increases in literacy, and global food production) have given rise to
trends that have caused environmental decay "in an ever more polluted
world among ever decreasing resources."
Hope, however, existed for traditional lifestyles. The report declared
that tribal and indigenous peoples had lifestyles that could provide
modern societies with lessons in the management of resources in complex
forest, mountain, and dryland ecosystems.
Differences from science
Comparing TEK and Western Science
Fulvio Mazzocchi of the Italian National Research Council's Institute of Atmospheric Pollution contrasts traditional knowledge from scientific knowledge as follows:
Traditional knowledge has developed
a concept of the environment that emphasizes the symbiotic character of
humans and nature. It offers an approach to local development that is
based on co‐evolution with the environment, and on respecting the
carrying capacity of ecosystems. This knowledge--based on long‐term
empirical observations adapted to local conditions--ensures a sound use
and control of the environment, and enables indigenous people to adapt
to environmental changes. Moreover, it supplies much of the world's
population with the principal means to fulfil their basic needs, and
forms the basis for decisions and strategies in many practical aspects,
including interpretation of meteorological phenomena, medical treatment,
water management, production of clothing, navigation, agriculture and
husbandry, hunting and fishing, and biological classification
systems.... Beyond its obvious benefit for the people who rely on this
knowledge, it might provide humanity as a whole with new biological and
ecological insights; it has potential value for the management of
natural resources and might be useful in conservation education as well
as in development planning and environmental assessment...Western
science is positivist and materialist in contrast to traditional
knowledge, which is spiritual and does not make distinctions between
empirical and sacred. Western science is objective and quantitative as
opposed to traditional knowledge, which is mainly subjective and
qualitative. Western science is based on an academic and literate
transmission, while traditional knowledge is often passed on orally from
one generation to the next by the elders.
Aspects of traditional ecological knowledge
The
aspects of traditional ecological knowledge provide different
typologies in how it is utilized and understood. These are good
indicators in how it is used from different perspectives and how they
are interconnected, providing more emphasis on "cooperative management
to better identify areas of difference and convergence when attempting
to bring two ways of thinking and knowing together."
Factual observations
Houde identifies six faces of traditional ecological knowledge.
The first aspect of traditional ecological knowledge incorporates the
factual, specific observations generated by recognition, naming, and
classification of discrete components of the environment. This aspect
is about understanding the interrelationship with species and their
surrounding environment. It is also a set of both empirical observations
and information emphasizing the aspects of animals and their behavior,
and habitat, and the physical characteristics of species, and animal
abundance. This is most useful for risk assessment and management which
provides nations with opportunity to influence resource management.
However, if a nation does not act, then the state may act on its own
interests. This type of "empirical knowledge consists of a set of
generalized observations conducted over a long period of time and
reinforced by accounts of other TEK holders."
Management systems
The
second face refers to the ethical and sustainable use of resources in
regards to management systems. This is achieved through strategic
planning to ensure resource conservation. More specifically this face
involves dealing with pest management, resource conversion, multiple
cropping patterns, and methods for estimating the state of resources. It also focuses on resource management and how it adapts to local environments.
Past and current uses
The
third face refers to the time dimension of TEK, focusing on past and
current uses of the environment transmitted through oral history,
such as land use, settlement, occupancy, and harvest levels.
Specifically medicinal plants and historical sites are great concerns.
Oral history is used to transmit cultural heritage generation to
generation, and contributes to a sense of family and community.
Ethics and values
The
fourth face refers to value statements and connections between the
belief system and the organization of facts. In regards to TEK it refers
to environmental ethics that keeps exploitative abilities in check.
This face also refers to the expression of values concerning the
relationship with the habitats of species and their surrounding
environment - the human-relationship environment.
Culture and identity
Traditional Ecological Knowledge frequently relates to knowledge surrounding plants and foliage.
The fifth face refers to the role of language and images of the past giving life to culture.
The relationship between Aboriginals (original inhabitants) and their
environment is vital to sustaining the cultural components that define
them. This face reflects the stories, values, and social relations that
reside in places as contributing to the survival, reproduction, and
evolution of aboriginal cultures, and identities. It also stresses "the
restorative benefits of cultural landscapes as places for renewal"
Cosmology
The
sixth face is a culturally based cosmology that is the foundation of
the other aspects. Cosmology is the notion of how the world works for
many cultures. This can vary greatly from one culture to the next. In
the U.S for example, there are over 577 federally recognized tribes with
their own culture, languages and belief system. Many of these tribes
understand themselves as interconnected with the land. The term
'cosmology' relates to the assumptions and beliefs about how things
work, and explains the way in which things are connected, and gives
principles that regulate human-animal relations and the role of humans
in the world. From an anthropological perspective, cosmology attempts to
understand the human-animal relationship and how these directly
influence social relationships, obligations toward community members,
and management practices.
In A Yupiaq Worldview: A Pathway to Ecology and Spirit by Angayuqaq Oscar Kawagley, an Indigenous
anthropologist, says "The balance of nature, or ecological perspective,
was of utmost importance to the Yupiaq. History and archeological
findings of different race in the world seem to indicate a common
philosophical or ecological thread among all people, and this apparent
linking leads to the concept of interconnectedness of all things of the
universe. The Yupiaq people were, and still are, proponents of this
worldview, in spite of the weakening of the ecological perspective by
modern intrusions." Kawagley elaborates more on TEK in the Yupiaqworldview
by saying that, "The Yupiaq person's methodologies include observation,
experience, social interaction, and listening to the conversations and
interrogations of the natural and spiritual worlds with the mind. The
person is always a participant-observer."
An
example of this is the Australian government giving back land to the
Aboriginal people to practice their tradition of controlled fires. This
made the areas more biologically diverse and decreased the threat of
wildfires and their severity.
Ecosystem management is a multifaceted and holistic approach to natural resource management.
It incorporates both science and traditional ecological knowledge to
collect data from long term measures that science cannot. This is
achieved by scientists and researchers collaborating with Indigenous
peoples through a consensus decision-making process while meeting the
socioeconomic, political and cultural needs of current and future
generations. Indigenous knowledge has developed a way to deal with the
complexity while western science has the techniques and tools. This is a
good relationship to have which creates a better outcome for both sides
and the environment. The dangers of working together is that nations do
not benefit fairly or at all. Many times Indigenous knowledge has been
used outside of the nation without consent (cultural appropriation), acknowledgment, or compensation. Indigenous knowledge can sustain the environment, yet it can be sacred knowledge.
Ecological restoration
Ecological restoration
is the practice of restoring a degraded ecosystem through human
intervention. There are many links between ecological restoration and
ecosystem management practices involving TEK, however TEK ecosystem
management is much more in-depth through the historical relationship
with the place.
Due to the aforementioned unequal power between indigenous and
non-indigenous peoples, it is vital that partnerships are equitable to
restore social injustices and this has proven to be successful when
Indigenous Peoples lead ecological restoration projects.
Traditional knowledge and the U.S. Environmental Protection Agency
The U.S. Environmental Protection Agency was one of the first federal
agencies to develop formal policies detailing how it would collaborate
with tribal governments and acknowledge tribal interests in enacting its
programs "to protect human health and the environment." In recognizing tribal peoples connection to the environment the EPA
has sought to develop environmental programs that integrate traditional
ecological knowledge into the "agency's environmental science, policy,
and decision-making processes."
Although TEK is not currently recognized as an important
component of mainstream environmental decision making, scientists are
working on developing core science competency programs that align with
TEK and promote self-sufficiency and determination.
The lack of recognition for traditional ecological knowledge in
determining solutions to environmental issues is representational of the
ethnocentric tendency to value science over traditional models.
Therefore, agencies integrating science and TEK must acknowledge the
values of unique pedagogical methods in order to fully utilize the
benefits of both science and TEK. For example, US agencies must learn
about TEK through the lens of indigenous groups by working side by side
with Indigenous Elders, gather hands-on data from the specific place in
question, and incorporating indigenous values into their scientific
evaluation.
In November 2000, U.S. President Bill Clinton
issued Executive Order 13175, which required federal departments and
agencies to consult with Indian Tribal governments in the development of
policies that would have Tribal implications.
Tribal Implications are defined by the EPA as having "substantial
direct effects on one or more Indian tribes, on the relationship between
the federal government and Indian tribes, or on the distribution of
power and responsibilities between the federal government and Indian
tribes."
As a Federal agency of the U.S. government, the EPA was required to
establish a set of standards for the consultation process. As its
initial response, the agency developed a set of standards that would
allow for meaningful communication and coordination between the agency
and tribal officials prior to the agency taking actions or implementing
decisions that may affect tribes. The standards also designated EPA
consultation contacts to promote consistency and coordination of the
consultation process, and established management oversight and reporting
to ensure accountability and transparency.
One form of consultation has been EPA Tribal Councils. In 2000,
the EPA's Office of Research and Development formed the EPA Tribal
Science Council. The council, made up of representatives from tribes
across the nation, is meant to provide a structure for tribal
involvement in EPA's science efforts, and serve as a vehicle through
which EPA may gain an understanding of the scientific issues that are of
highest priority to tribes at a national level. The council also offers
tribes an opportunity to influence EPA's scientific agenda by raising
these priority issues to an EPA-wide group.
Of importance for tribal members at the initial gathering of the
EPA Tribal Science Council was the inherent differences in tribal
traditional lifeways and western science. These lifeways include
"spiritual, emotional, physical, and mental connections to the
environment; connections which are based on intrinsic, immeasurable
values"; and an understanding that the earth's resources will provide
everything necessary for human survival.
The EPA's Tribal Science Council, however, was meant to act as a
meeting place where both groups could "share information that may
contribute to environmental protection for all peoples with neither
culture relinquishing its identity." In an effort to protect TTL the
Council identified subsitence as a critical area for investigation. The
EPA-Tribal Science Council defined subsistence as: the "relationships
between people and their surrounding environment, a way of living.
Subsistence involves an intrinsic spiritual connection to the earth, and
includes an understanding that the earth's resources will provide
everything necessary for human survival. People who subsist from the
earth's basic resources remain connected to those resources, living
within the circle of life. Subsistence is about living in a way that
will ensure the integrity of the earth's resources for the beneficial
use of generations to come." Because TTL or TEK is specific to a
location and includes the relationships between plants and animals, and
the relationship of living beings to the environment, acknowledgment of
subsitence as a priority allows for the knowledge and practices of TTL
to be protected. For example, as part of their deliberation regarding
subsistence, the Council agreed to identify resource contamination as
"the most critical tribal science issue at this time." Because tribal
people with subsistence lifestyles rely the environment for traditional
techniques of farming, hunting. fishing, forestry, and medicines, and
ceremonies, contaminants disproportionately impact tribal peoples and
jeopardizes their TTL. As the EPA Council stated, "Tribal subsistence
consumption rates are typically many times higher than those of the
general population, making the direct impact of resource contamination a
much more immediate concern." As native peoples struggle with tainted resources, the council has made progress in investigating its impacts.
Despite such efforts, there are still barriers to progress within
the EPA-Tribal Science Council. For example, one obstacle has been the
nature of TTL. Tribal Traditional Lifeways are passed down orally, from
person to person, generation to generation, whereas western science
relies on the written word, communicated through academic and literate
transmission.
Endeavors to bring together western scientists and tribal people have
also been hindered by Native American's perceptions that scientific
analysis are put in a metaphorical "black box" that shuts out tribal
input. Regardless, the EPA has recognized the ability of indigenous
knowledge to advance scientific understanding and provide new
information and perspectives that may benefit the environment and human
health.
The integration of TTL into the EPA's risk assessment paradigm is
one example of how the EPA-Tribal Science Council has been able to
enact change in EPA culture. The risk assessment paradigm is an
"organizing framework for the scientific analysis of the potential for
harmful impacts to human health and the environment as a result of
exposure to contaminants or other environmental stressors." Risk
assessment has been used by the EPA to establish "clean-up levels at
hazardous waste sites, water quality and air quality criteria, fish
advisories, and bans or restricted uses for pesticides and other toxic
chemicals."
Tribal people are concerned, however, that current risk assessment
methodologies do not afford complete value to tribal culture, values,
and/or life ways. The Tribal Science Council seeks to incorporate TTL
into exposure assumptions existent in the EPA risk assessment model. A
long-term goal for the EPA's Tribal Science Council, however, is a
complete shift in decision-making assessments from risk to preserving a
healthy people and environment. As stated above, tribal people do not
accept a separation of the human and ecological condition when they
characterize risk. Through EPA initiated seminar, workshops, and
projects, tribes have been able to engage in dialogue about the
integration of Tribal Traditional Lifeways into EPA risk assessment and
decision-making. This has occurred in a number of ways: inclusion of
unique tribal cultural activities such as native basketry, the
importance of salmon and other fishes, native plant medicine,
consumption of large amounts of fish and game, and sweat lodges as
exposures for estimating potential risk to people or to communities.
Although these types of tribal specific activities may be included in
EPA's risk assessment, there is no assurance that they will be included
nor is there consistency in how they may be applied at different sites
across the country.
In July 2014, the EPA announced its "Policy on Environmental
Justice for Working with Federally Recognized Tribes and Indigenous
Peoples," setting forth its principles for programs related to federally recognized tribes
and indigenous peoples in order to "support the fair and effective
implementation of federal environmental laws, and provide protection
from disproportionate impacts and significant risks to human health and
the environment."
Among the 17 principles were #3 ("The EPA works to understand
definitions of human health and the environment from the perspective of
federally recognized tribes, indigenous peoples throughout the United
States, and others living in Indian country"); #6 ("The EPA encourages,
as appropriate and to the extent practicable and permitted by law, the
integration of traditional ecological knowledge into the agency's
environmental science, policy, and decision-making processes, to
understand and address environmental justice concerns and facilitate
program implementation"); and #7 ("The EPA considers confidentiality
concerns regarding information on sacred sites, cultural resources, and
other traditional knowledge, as permitted by law.").
While this policy identifies guidelines and procedures for the EPA in
regards to environmental justice principles as they relate to tribes and
indigenous peoples, the agency noted that they are in no way applicable
as rules or regulations.
They cannot be applied to particular situations nor change or
substitute any law, regulation, or any other legally-binding requirement
and is not legally enforceable.
Effects of environmental degradation on traditional knowledge
In some areas, environmental degradation has led to a decline in traditional ecological knowledge. For example, at the Aamjiwnaang community of Anishnaabe First Nations people in Sarnia, Ontario, Canada, residents suffer from a "noticeable decrease in male birth ratio ..., which residents attribute to their proximity to petrochemical plants":
In addition to concerns about the
physical reproduction of community members, indigenous people are
concerned about how environmental contamination impacts the reproduction
of cultural knowledge. In Aamjiwnaang, oral traditions once passed down
from grandfathers during fishing or grandmothers during berry picking
and medicine gathering are being lost as those activities are no longer
practiced because of concerns about these foods being contaminated.
Rocks once used for sweat lodges are no longer being collected from
local streams because the streams have become contaminated. The cedar
used for making tea, smudging, and washing babies contains vanadium at
concentrations as high as 6 mg/kg..., reflecting local releases to air
of > 611 tons of vanadium between 2001 and 2010.... At Akwesasne,
community members report a loss of language and culture around
subsistence activities like fishing, which have been largely abandoned
because of fears of exposure to contaminants.
Traditional ecological knowledge provides information about climate
change across generations and geography of the actual residents in the
area.
Traditional ecological knowledge emphasizes and makes the information
about the health and interactions of the environment the center of the
information it carries. Climate change
affects traditional ecological knowledge in the forms of the indigenous
people's identity and the way they live their lives. Traditional
knowledge is passed down from generation to generation and continues
today. Indigenous people depend on these traditions for their
livelihood. For many harvesting seasons, indigenous people have shifted
their activity months earlier due to impacts from climate change.
The rising temperature poses as threats for ecosystems because it
harms the livelihoods of certain tree and plant species. The
combination of the rise in temperatures and change in precipitation
levels affects plant growth locations.
The warming also affects insects and animals. The change in
temperatures can affect many aspects from the times that insects emerge
throughout the year to the changes in the habitats of animals throughout
seasonal changes.
As the temperature gets hotter, wild fires become more likely.
One Indigenous nation in Australia was recently given back land and are
reinstating their traditional practice of controlled burning. This has
resulted in increased biodiversity and decreased severity of wildfires.
Not only are different aspects of the environment affected, but
together, the health of the ecosystem is affected by climate change and
so the environmental resources available to the indigenous people can
change in the amount available and the quality of the resources.
As sea ice levels decrease, Alaska Native peoples experience
changes in their daily lives; fishing, transportation, social and
economic aspects of their lives become more unsafe.
The defrosting of soil has caused damages to buildings and roadways.
Water contamination becomes exacerbated as clean water resources
dwindle.
Climate changes undermine the daily lives of the Native peoples on many levels. Climate change and indigenous people
have a varying relationship depending on the geographic region which
require different adaption and mitigation actions. For example, to
immediately deal with these conditions, the indigenous people adjust
when they harvest and what they harvest and also adjust their resource
use. Climate change can change the accuracy of the information of
traditional ecological knowledge. The indigenous people have relied
deeply on indicators in nature to plan activities and even for short-
term weather predictions.
As a result of even more increasing unfavorable conditions, the
indigenous people relocate to find other ways to survive. As a result,
there is a loss of cultural ties to the lands they once resided on and
there is also a loss to the traditional ecological knowledge they had
with the land there. Climate change adaptations not properly structured or implemented can harm the indigenous people's rights.
In
one study, villagers of Savoonga and Shaktoolik, Alaska reported that
over the last twenty years of their lives, the weather has become more
difficult to predict, the colder season has shortened, there is more
difficulty in predicting the amount of plants available for harvests,
there are differences in animal migrations, there are more sightings of
new species than before, and the activities of hunting and gathering
have become not as predictable nor occur as often due to more limited
availability to do so. The residents saw a noticeable change in their
climate which also affected their livelihoods. The plants and animals
are not as consistent with their availability which affects the
residents' hunting and gathering because there is not as much to hunt or
gather. The appearance of new species of plants and animals is also a
physical and nutritional safety concern because they are not
traditionally part of the land.
Tribally Specific TEK
Karuk and Yurok Burning as TEK
According
to environmental sociologist Kirsten Vinyeta and tribal climate change
researcher Kathy Lynn, "the Karuk Tribe of California occupies
aboriginal land along the middle course of the Klamath and Salmon Rivers
in Northern California. The Tribe's aboriginal territory includes an
estimated 1.38 million acres within the Klamath River Basin. Traditional
burning practices have been critical to the Karuk since time
immemorial. For the Tribe, fire serves as a critical land management
tool as well as a spiritual practice."
According to environmental studies professor Tony Marks-Block,
ecological researcher Frank K. Lake and tropical forester Lisa M.
Curran, "before widespread fire exclusion policies, American Indians
used to broadcast understory fires or cultural burns to enhance
resources integral for their livelihood and cultural practices. To
restore ecocultural resources depleted from decades of fire exclusion
and to reduce wildfire risks, the Karuk and the Yurok Tribes of
Northwest California are leading regional collaborative efforts to
expand broadcast fires and fuel reduction treatments on public, private,
and Tribal lands in their ancestral territories."
Tony Marks-Block, Frank K. Lake and Lisa M. Curran also state
that "in Karuk territory, the federal government did not establish a
reservation, leaving merely 3.83 square kilometers of Karuk trust lands
in their ancestral territory, with the remainder largely under the
jurisdiction of the Klamath and Six Rivers National Forests and
scattered private homesteads. As a result, Karuk Tribal members and
management agencies must navigate the USDA Forest Service claims on
their ancestral territory and have limited options to expand their land
base through the acquisition of private land holdings. In Yurok
territory, multiple overlapping jurisdictions occur including Redwood
National Park and Six Rivers National Forest outside of the reservation
established by the federal government. The reservation is under private
timber company ownership. Consequently, the Yurok Tribe must either
coordinate or interact with multiple actors within their ancestral
territory, but they presently have greater options for acquiring private
properties than the Karuk Tribe."
According to professor of sociology Kari Norgaard and Karuk tribe
member William Tripp, "this process can then be replicated and expanded
to other communities throughout the western Klamath Mountains and
beyond. Hoopa and Yurok tanoak stands that experienced repeated fire
were more resilient to the disease over time. Some research indicates
dramatic differences in disease incidence immediately following wildfire
(72 times less likely to be found in burned versus unburned plots in
the same area), although it has been shown to steadily recover in the
absence of repeated fire, because the disease can survive in hosts not
killed by the fire."
Anishinabe Ecological Conservation as TEK
According
to authors Bobbie Kalman and Niki Walker, "indigenous, or Native,
people have lived in the Great Lakes region for thousands of years.
People of the Anishinabe (Anishinaabe) nation lived in territories in
the western Great Lakes region. According to oral tradition, the
Anishinabe people once lived by a huge body of salt water, which may
have been the Atlantic Ocean or Hudson's Bay. The people received a
prophecy, or prediction, that if they traveled inland, they would find a
place where food grew on water. Some went west, following a vision of a
megis, or cowrie shell, that guided them to the western Great Lakes.
The people split into groups and settled in different spots that
together made up the Anishinabe nation. The Anishinabe had an especially
close relationship with two other nations in the western Great Lakes
region being the Odawa (Ottawa) and Potawatomi. People of these three
nations often married one another, traded goods, and worked together to
settle disputes. They also gathered at councils, where they made
decisions together."
According to indigenous philosopher and climate/environmental
justice scholar Kyle Powys Whyte, "Anishinabe people throughout the
Great Lakes region are at the forefront of native species conservation
and ecological restoration. Nmé is the largest and oldest living fish in
the Great Lakes basin, sometimes exceeding 100 years in age. Nmé served
the Asnishinabe people as a substantial source of food, an indicator
species for monitoring the environment, and a lachlan identity, playing a
role in ceremonies and stories. Kenny Pheasant, an elder says, "Decline
of the sturgeon has corresponded with decline in sturgeon clan
families. Only a few sturgeon clan families are known around here"
(Little River Band). The Natural Resources Department of the Ottawa
Indians started a cultural context group, composed of a diverse range of
tribal members and biologists, which developed goals and objectives for
restoration. The goal was to "restore the harmony and connectivity
between Nmé and the Anishinabe people and bring them both back to the
river. Ultimately, the department created the first streamside rearing
facility for protecting young sturgeon before they are released each
fall in order to preserve their genetic parentage. Wild rice, or
manoomin, grows in shallow, clear, and slow-moving waterways and can be
harvested in early autumn. After harvesting, manoomin is processed
through activities such as drying, parching, hulling, winnowing, and
cleaning. After the Anishinabe migrated from the East and reached the
Great Lakes region where they could grow crops on the water, neighboring
groups of US and Canadian citizens and companies engaged in activities
such as mining, damming, commercial farming and recreational boating.
These activities directly affect manoomin and its habitat. Today the
Anishinabe people are leaders in the conservation of wild rice. The Nibi
(water) and Manoomin Symposium, which takes place every two years,
brings tribal rice harvesters in the Great Lakes, indigenous scholars,
paddy rice growers, representatives from mining companies and state
agencies, and university researchers interested in the genetic
modification of rice together. Elders share their stories about manoomin
and youth share their perspective on how manoomin fits into their
futures. Indigenous persons working as scientists in their tribes share
the experiences working with elders to understand the deep historical
implications of the work they do to study and conserve manoomin. Other
indigenous people are often invited to share their experiences restoring
and conserving other native species, such as taro and maize."
Lummi Nation of Washington State Conservation of Southern Resident Killer Whales as TEK
According
to ecological scholars Paul Guernsey, Kyle Keeler and Lummi member
Jeremiah Julius, "the Lummi Nation of Washington State is a native
American tribe of the Salish Sea. In 2018, the Lummi Nation dedicated
itself to a Totem Pole Journey across the United States calling for the
return of their relative "Lolita" (a Southern Resident Killer Whale) to
her home waters. In the Salish language, killer whales are referred to
as qwe 'lhol mechen, meaning 'our relations under the waves', but the
Lummi are not simply 'related to' the whales in a generic fashion, the
whales are a relation in the sense that they are kin. When NOAA first
designated the Southern Resident killer whale an endangered distinct
population segment (DPS) in 2005, they juridically eliminated "Lolita"
as a family member. The decision reads, "The Southern Resident killer
whale DPS does not include killer whales from J, K or L pod placed in
captivity prior to listing, nor does it include their captive born
progeny" (NOAA, 2005). The Lummi are asking for NOAA to collaborate in
feeding the whales until the chinook runs of the Puget Sound can sustain
them. The Lummi have embarked on ceremonial feedings of their
relatives, but they are told by NOAA that larger-scale efforts would
require federal permission and partnership. Although one of the
organization's conservation goals is to ensure 'sufficient quantity,
quality and accessibility of prey species', NOAA understands this policy
strictly as a habitat issue. They have been clear that now is not the
time for complacency due to 'insufficient data' or uncertainty. The
Lummi continue their annual Totem Pole Journey to protect their older
siblings, the blackfish, and to keep coal, oil and other threats out of
the Salish Sea. These healing practices are fashioned to address what
Maria Yellow Horse Brave Heart and Lemyra M. DeBruyn have called
"historical unresolved grief"."
Lack of the plant hormone auxin can cause abnormal growth (right)
Plant hormones (or phytohormones) are signal molecules, produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of plant growth and development, from embryogenesis, the regulation of organ size, pathogen defense,stress tolerance and through to reproductive development. Unlike in animals (in which hormone production is restricted to specialized glands) each plant cell is capable of producing hormones. Went and Thimann coined the term "phytohormone" and used it in the title of their 1937 book.
Phytohormones occur across the plant kingdom, and even in algae, where they have similar functions to those seen in higher plants. Some phytohormones also occur in microorganisms, such as unicellular fungi and bacteria, however in these cases they do not play a hormonal role and can better be regarded as secondary metabolites.
Characteristics
Phyllody on a purple coneflower (Echinacea purpurea), a plant development abnormality where leaf-like structures replace flower organs. It can be caused by hormonal imbalance, among other reasons.
The word hormone is derived from Greek, meaning set in motion. Plant hormones affect gene expression and transcription
levels, cellular division, and growth. They are naturally produced
within plants, though very similar chemicals are produced by fungi and
bacteria that can also affect plant growth. A large number of related chemical compounds are synthesized by humans. They are used to regulate the growth of cultivated plants, weeds, and in vitro-grown plants and plant cells; these manmade compounds are called plant growth regulators (PGRs). Early in the study of plant hormones, "phytohormone" was the commonly used term, but its use is less widely applied now.
Plant hormones are not nutrients, but chemicals that in small amounts promote and influence the growth, development, and differentiation of cells and tissues.
The biosynthesis of plant hormones within plant tissues is often
diffuse and not always localized. Plants lack glands to produce and
store hormones, because, unlike animals—which have two circulatory
systems (lymphatic and cardiovascular) powered by a heart
that moves fluids around the body—plants use more passive means to move
chemicals around their bodies. Plants utilize simple chemicals as
hormones, which move more easily through their tissues. They are often
produced and used on a local basis within the plant body. Plant cells
produce hormones that affect even different regions of the cell
producing the hormone.
Hormones are transported within the plant by utilizing four types of movements. For localized movement, cytoplasmic streaming within cells and slow diffusion of ions and molecules between cells are utilized. Vascular tissues are used to move hormones from one part of the plant to another; these include sieve tubes or phloem that move sugars from the leaves to the roots and flowers, and xylem that moves water and mineral solutes from the roots to the foliage.
Not all plant cells respond to hormones, but those cells that do
are programmed to respond at specific points in their growth cycle. The
greatest effects occur at specific stages during the cell's life, with
diminished effects occurring before or after this period. Plants need
hormones at very specific times during plant growth and at specific
locations. They also need to disengage the effects that hormones have
when they are no longer needed. The production of hormones occurs very
often at sites of active growth within the meristems,
before cells have fully differentiated. After production, they are
sometimes moved to other parts of the plant, where they cause an
immediate effect; or they can be stored in cells to be released later.
Plants use different pathways to regulate internal hormone quantities
and moderate their effects; they can regulate the amount of chemicals
used to biosynthesize hormones. They can store them in cells,
inactivate them, or cannibalise already-formed hormones by conjugating them with carbohydrates, amino acids, or peptides.
Plants can also break down hormones chemically, effectively destroying
them. Plant hormones frequently regulate the concentrations of other
plant hormones. Plants also move hormones around the plant diluting their concentrations.
The concentration of hormones required for plant responses are very low (10−6 to 10−5mol/L).
Because of these low concentrations, it has been very difficult to
study plant hormones, and only since the late 1970s have scientists been
able to start piecing together their effects and relationships to plant
physiology.
Much of the early work on plant hormones involved studying plants that
were genetically deficient in one or involved the use of
tissue-cultured plants grown in vitro
that were subjected to differing ratios of hormones, and the resultant
growth compared. The earliest scientific observation and study dates to
the 1880s; the determination and observation of plant hormones and their
identification was spread out over the next 70 years.
Classes
Different
hormones can be sorted into different classes, depending on their
chemical structures. Within each class of hormone, chemical structures
can vary, but all members of the same class have similar physiological
effects. Initial research into plant hormones identified five major
classes: abscisic acid, auxins, brassinosteroids, cytokinins and
ethylene.
This list was later expanded, and brassinosteroids, jasmonates,
salicylic acid, and strigolactones are now also considered major plant
hormones. Additionally there are several other compounds that serve
functions similar to the major hormones, but their status as bone fide hormones is still debated.
Abscisic acid
Abscisic acid
Abscisic acid
(also called ABA) is one of the most important plant growth inhibitors.
It was discovered and researched under two different names, dormin and abscicin II,
before its chemical properties were fully known. Once it was determined
that the two compounds are the same, it was named abscisic acid. The
name refers to the fact that it is found in high concentrations in newly
abscissed or freshly fallen leaves.
This class of PGR is composed of one chemical compound normally produced in the leaves of plants, originating from chloroplasts, especially when plants are under stress. In general, it acts as an inhibitory chemical compound that affects bud growth, and seed and bud dormancy. It mediates changes within the apical meristem,
causing bud dormancy and the alteration of the last set of leaves into
protective bud covers. Since it was found in freshly abscissed leaves,
it was initially thought to play a role in the processes of natural leaf
drop, but further research has disproven this. In plant species from
temperate parts of the world, abscisic acid plays a role in leaf and
seed dormancy by inhibiting growth, but, as it is dissipated from seeds
or buds, growth begins. In other plants, as ABA levels decrease, growth
then commences as gibberellin
levels increase. Without ABA, buds and seeds would start to grow during
warm periods in winter and would be killed when it froze again. Since
ABA dissipates slowly from the tissues and its effects take time to be
offset by other plant hormones, there is a delay in physiological
pathways that provides some protection from premature growth. Abscisic
acid accumulates within seeds during fruit maturation, preventing seed
germination within the fruit or before winter. Abscisic acid's effects
are degraded within plant tissues during cold temperatures or by its
removal by water washing in and out of the tissues, releasing the seeds
and buds from dormancy.
ABA exists in all parts of the plant, and its concentration
within any tissue seems to mediate its effects and function as a
hormone; its degradation, or more properly catabolism, within the plant affects metabolic reactions and cellular growth and production of other hormones.
Plants start life as a seed with high ABA levels. Just before the seed
germinates, ABA levels decrease; during germination and early growth of
the seedling, ABA levels decrease even more. As plants begin to produce
shoots with fully functional leaves, ABA levels begin to increase again,
slowing down cellular growth in more "mature" areas of the plant.
Stress from water or predation affects ABA production and catabolism
rates, mediating another cascade of effects that trigger specific
responses from targeted cells. Scientists are still piecing together the
complex interactions and effects of this and other phytohormones.
In plants under water stress, ABA plays a role in closing the stomata.
Soon after plants are water-stressed and the roots are deficient in
water, a signal moves up to the leaves, causing the formation of ABA
precursors there, which then move to the roots. The roots then release
ABA, which is translocated to the foliage through the vascular system and modulates potassium and sodium uptake within the guard cells, which then lose turgidity, closing the stomata.
Auxins
The auxin, indole-3-acetic acid
Auxins
are compounds that positively influence cell enlargement, bud
formation, and root initiation. They also promote the production of
other hormones and, in conjunction with cytokinins, control the growth of stems, roots, and fruits, and convert stems into flowers. Auxins were the first class of growth regulators discovered.
A Dutch Biologist Frits Warmolt Went first described auxins. They affect cell elongation by altering cell wall plasticity. They stimulate cambium, a subtype of meristem cells, to divide, and in stems cause secondary xylem to differentiate.
Auxins act to inhibit the growth of buds lower down the stems in a phenomenon known as apical dominance, and also to promote lateral and adventitious root
development and growth. Leaf abscission is initiated by the growing
point of a plant ceasing to produce auxins. Auxins in seeds regulate
specific protein synthesis, as they develop within the flower after pollination, causing the flower to develop a fruit to contain the developing seeds.
Brassinosteroids
are a class of polyhydroxysteroids, the only example of steroid-based
hormones in plants. Brassinosteroids control cell elongation and
division, gravitropism, resistance to stress, and xylem differentiation. They inhibit root growth and leaf abscission. Brassinolide was the first identified brassinosteroid and was isolated from extracts of rapeseed (Brassica napus) pollen in 1979.
Brassinosteroids are a class of steroidal phytohormones in plants that
regulate numerous physiological processes. This plant hormone was
identified by Mitchell et al. who extracted ingredients from Brassica
pollen only to find that the extracted ingredients’ main active
component was Brassinolide.
This finding meant the discovery of a new class of plant hormones
called Brassinosteroids. These hormones act very similarly to animal
steroidal hormones by promoting growth and development. In plants these
steroidal hormones play an important role in cell elongation via BR
signaling.
Brassinosteroids receptor- brassinosteroid insensitive 1 (BRI1) is the
main receptor for this signaling pathway. This BRI1 receptor was found
by Clouse et al. who made the discovery by inhibiting BR and comparing
it to the wildtype in Arabidopsis. The BRI1 mutant displayed several
problems associated with growth and development such as dwarfism, reduced cell elongation and other physical alterations.
These findings mean that plants properly expressing brassinosteroids
grow more than their mutant counterparts. Brassinosteroids bind to BRI1
localized at the plasma membrane
which leads to a signal cascade that further regulates cell elongation.
This signal cascade however is not entirely understood at this time.
What is believed to be happening is that BR binds to the BAK1 complex
which leads to a phosphorylation cascade. This phosphorylation cascade then causes BIN2 to be deactivated which causes the release of transcription factors. These released transcription factors then bind to DNA that leads to growth and developmental processes and allows plants to respond to abiotic stressors.
Cytokinins or CKs are a group of chemicals that influence cell division and shoot formation. They also help delay senescence
of tissues, are responsible for mediating auxin transport throughout
the plant, and affect internodal length and leaf growth. They were
called kinins in the past when they were first isolated from yeast
cells. Cytokinins and auxins often work together, and the ratios of
these two groups of plant hormones affect most major growth periods
during a plant's lifetime. Cytokinins counter the apical dominance
induced by auxins; in conjunction with ethylene, they promote abscission
of leaves, flower parts, and fruits.
Among the plant hormones, the 3 that are known to help with
immunological interactions are ethylene (ET), salicylates (SA), and
jasmonates (JA), however more research has gone into identifying the
role that cytokinins (CK) play in this. Evidence suggests that
cytokinins delay the interactions with pathogens, showing signs that
they could induce resistance toward these pathogenic bacteria.
Accordingly, there are higher CK levels in plants that have increased
resistance to pathogens compared to those which are more susceptible. For example, pathogen resistance involving cytokinins was tested using the Arabidopsis species by treating them with naturally occurring CK (trans-zeatin) to see their response to the bacteria Pseudomonas syringa.
Tobacco studies reveal that over expression of CK inducing IPT genes
yields increased resistance whereas over expression of CK oxidase yields
increased susceptibility to pathogen, namely P. syringae.
While there’s not much of a relationship between this hormone and
physical plant behavior, there are behavioral changes that go on inside
the plant in response to it. Cytokinin defense effects can include the
establishment and growth of microbes (delay leaf senescence),
reconfiguration of secondary metabolism or even induce the production of
new organs such as galls or nodules. These organs and their corresponding processes are all used to protect the plants against biotic/abiotic factors.
Unlike the other major plant hormones, ethylene is a gas and a very simple organic compound, consisting of just six atoms. It forms through the breakdown of methionine,
an amino acid which is in all cells. Ethylene has very limited
solubility in water and therefore does not accumulate within the cell,
typically diffusing out of the cell and escaping the plant. Its
effectiveness as a plant hormone is dependent on its rate of production
versus its rate of escaping into the atmosphere. Ethylene is produced at
a faster rate in rapidly growing and dividing cells, especially in
darkness. New growth and newly germinated seedlings produce more
ethylene than can escape the plant, which leads to elevated amounts of
ethylene, inhibiting leaf expansion (see hyponastic response).
As the new shoot is exposed to light, reactions mediated by phytochrome
in the plant's cells produce a signal for ethylene production to
decrease, allowing leaf expansion. Ethylene affects cell growth and cell
shape; when a growing shoot or root hits an obstacle while underground,
ethylene production greatly increases, preventing cell elongation and
causing the stem to swell. The resulting thicker stem is stronger and
less likely to buckle under pressure as it presses against the object
impeding its path to the surface. If the shoot does not reach the
surface and the ethylene stimulus becomes prolonged, it affects the
stem's natural geotropic
response, which is to grow upright, allowing it to grow around an
object. Studies seem to indicate that ethylene affects stem diameter and
height: when stems of trees are subjected to wind, causing lateral
stress, greater ethylene production occurs, resulting in thicker,
sturdier tree trunks and branches.
Ethylene also affects fruit ripening. Normally, when the seeds
are mature, ethylene production increases and builds up within the
fruit, resulting in a climacteric
event just before seed dispersal. The nuclear protein Ethylene
Insensitive2 (EIN2) is regulated by ethylene production, and, in turn,
regulates other hormones including ABA and stress hormones.
Ethylene diffusion out of plants is strongly inhibited underwater. This
increases internal concentrations of the gas. In numerous aquatic and
semi-aquatic species (e.g. Callitriche platycarpus, rice, and Rumex palustris),
the accumulated ethylene strongly stimulates upward elongation. This
response is an important mechanism for the adaptive escape from
submergence that avoids asphyxiation by returning the shoot and leaves
to contact with the air whilst allowing the release of entrapped
ethylene. At least one species (Potamogeton pectinatus)
has been found to be incapable of making ethylene while retaining a
conventional morphology. This suggests ethylene is a true regulator
rather than being a requirement for building a plant's basic body plan.
Gibberellins
Gibberellin A1
Gibberellins
(GAs) include a large range of chemicals that are produced naturally
within plants and by fungi. They were first discovered when Japanese
researchers, including Eiichi Kurosawa, noticed a chemical produced by a
fungus called Gibberella fujikuroi that produced abnormal growth in rice plants.
It was later discovered that GAs are also produced by the plants
themselves and control multiple aspects of development across the life
cycle. The synthesis of GA is strongly upregulated in seeds at
germination and its presence is required for germination to occur. In
seedlings and adults, GAs strongly promote cell elongation. GAs also
promote the transition between vegetative and reproductive growth and
are also required for pollen function during fertilization.
Gibberellins breaks the dormancy (in active stage) in seeds and
buds and helps increasing the height of the plant. It helps in the
growth of the stem.
Jasmonates
Jasmonic acid
Jasmonates (JAs) are lipid-based hormones that were originally isolated from jasmine oil. JAs are especially important in the plant response to attack from herbivores and necrotrophicpathogens. The most active JA in plants is jasmonic acid. Jasmonic acid can be further metabolized into methyl jasmonate (MeJA), which is a volatile organic compound.
This unusual property means that MeJA can act as an airborne signal to
communicate herbivore attack to other distant leaves within one plant
and even as a signal to neighboring plants.
In addition to their role in defense, JAs are also believed to play
roles in seed germination, the storage of protein in seeds, and root
growth.
JAs have been shown to interact in the signalling pathway of
other hormones in a mechanism described as “crosstalk.” The hormone
classes can have both negative and positive effects on each other's
signal processes.
Jasmonic acid methyl ester (JAME) has been shown to regulate genetic expression in plants. They act in signalling pathways in response to herbivory, and upregulate expression of defense genes. Jasmonyl-isoleucine
(JA-Ile) accumulates in response to herbivory, which causes an
upregulation in defense gene expression by freeing up transcription
factors.
Jasmonate mutants are more readily consumed by herbivores than
wild type plants, indicating that JAs play an important role in the
execution of plant defense. When herbivores are moved around leaves of
wild type plants, they reach similar masses to herbivores that consume
only mutant plants, implying the effects of JAs are localized to sites
of herbivory. Studies have shown that there is significant crosstalk between defense pathways.
Salicylic acid
Salicylic acid
Salicylic acid (SA) is a hormone with a structure related to phenol. It was originally isolated from an extract of white willow bark (Salix alba) and is of great interest to human medicine, as it is the precursor of the painkiller aspirin.
In plants, SA plays a critical role in the defense against biotrophic
pathogens. In a similar manner to JA, SA can also become methylated. Like MeJA, methyl salicylate
is volatile and can act as a long-distance signal to neighboring plants
to warn of pathogen attack. In addition to its role in defense, SA is
also involved in the response of plants to abiotic stress, particularly
from drought, extreme temperatures, heavy metals, and osmotic stress.
Salicylic acid (SA) serves as a key hormone in plant innate
immunity, including resistance in both local and systemic tissue upon
biotic attacks, hypersensitive responses, and cell death. Some of the SA
influences on plants include seed germination, cell growth,
respiration, stomatal closure, senescence-associated gene expression,
responses to abiotic and biotic stresses, basal thermo tolerance and
fruit yield. A possible role of salicylic acid in signaling disease
resistance was first demonstrated by injecting leaves of resistant
tobacco with SA.
The result was that injecting SA stimulated pathogenesis related (PR)
protein accumulation and enhanced resistance to tobacco mosaic virus
(TMV) infection. Exposure to pathogens causes a cascade of reactions in
the plant cells. SA biosynthesis is increased via isochorismate synthase
(ICS) and phenylalanine ammonia-lyase (PAL) pathway in plastids.
It was observed that during plant-microbe interactions, as part of the
defense mechanisms, SA is initially accumulated at the local infected
tissue and then spread all over the plant to induce systemic acquired
resistance at non-infected distal parts of the plant. Therefore with
increased internal concentration of SA, plants were able to build
resistant barriers for pathogens and other adverse environmental
conditions
Strigolactones (SLs) were originally discovered through studies of the germination of the parasitic weed Striga lutea. It was found that the germination of Striga species was stimulated by the presence of a compound exuded by the roots of its host plant. It was later shown that SLs that are exuded into the soil also promote the growth of symbioticarbuscular mycorrhizal (AM) fungi. More recently, another role of SLs was identified in the inhibition of shoot branching.
This discovery of the role of SLs in shoot branching led to a dramatic
increase in the interest in these hormones, and it has since been shown
that SLs play important roles in leaf senescence, phosphate starvation response, salt tolerance, and light signalling.
Other known hormones
Other identified plant growth regulators include:
Plant peptide hormones
– encompasses all small secreted peptides that are involved in
cell-to-cell signaling. These small peptide hormones play crucial roles
in plant growth and development, including defense mechanisms, the
control of cell division and expansion, and pollen self-incompatibility. The small peptide CLE25 is known to act as a long-distance signal to communicate water stress sensed in the roots to the stomata in the leaves.
Polyamines
– are strongly basic molecules with low molecular weight that have been
found in all organisms studied thus far. They are essential for plant
growth and development and affect the process of mitosis and meiosis. In
plants, polyamines have been linked to the control of senescence and programmed cell death.
Nitric oxide
(NO) – serves as signal in hormonal and defense responses (e.g.
stomatal closure, root development, germination, nitrogen fixation, cell
death, stress response).
NO can be produced by a yet undefined NO synthase, a special type of
nitrite reductase, nitrate reductase, mitochondrial cytochrome c oxidase
or non enzymatic processes and regulate plant cell organelle functions
(e.g. ATP synthesis in chloroplasts and mitochondria).
Karrikins
– are not plant hormones as they are not produced by plants themselves
but are rather found in the smoke of burning plant material. Karrikins
can promote seed germination in many species. The finding that plants which lack the receptor of karrikin receptor show several developmental phenotypes
(enhanced biomass accumulation and increased sensitivity to drought)
have led some to speculate on the existence of an as yet unidentified
karrikin-like endogenous hormone in plants. The cellular karrikin
signalling pathway shares many components with the strigolactone
signalling pathway.
Triacontanol – a fatty alcohol that acts as a growth stimulant, especially initiating new basal breaks in the rose family. It is found in alfalfa (lucerne), bee's wax, and some waxy leaf cuticles.
The propagation of plants by cuttings of fully developed leaves, stems, or roots is performed by gardeners utilizing auxin
as a rooting compound applied to the cut surface; the auxins are taken
into the plant and promote root initiation. In grafting, auxin promotes callus tissue formation, which joins the surfaces of the graft
together. In micropropagation, different PGRs are used to promote
multiplication and then rooting of new plantlets. In the
tissue-culturing of plant cells, PGRs are used to produce callus growth,
multiplication, and rooting.
Plant hormones affect seed germination and dormancy by acting on different parts of the seed.
Embryo dormancy is characterized by a high ABA:GA ratio, whereas
the seed has high abscisic acid sensitivity and low GA sensitivity. In
order to release the seed from this type of dormancy and initiate seed
germination, an alteration in hormone biosynthesis and degradation
toward a low ABA/GA ratio, along with a decrease in ABA sensitivity and
an increase in GA sensitivity, must occur.
ABA controls embryo dormancy, and GA embryo germination.
Seed coat dormancy involves the mechanical restriction of the seed coat.
This, along with a low embryo growth potential, effectively produces
seed dormancy. GA releases this dormancy by increasing the embryo
growth potential, and/or weakening the seed coat so the radical of the
seedling can break through the seed coat.
Different types of seed coats can be made up of living or dead cells,
and both types can be influenced by hormones; those composed of living
cells are acted upon after seed formation, whereas the seed coats
composed of dead cells can be influenced by hormones during the
formation of the seed coat. ABA affects testa or seed coat growth
characteristics, including thickness, and effects the GA-mediated embryo
growth potential. These conditions and effects occur during the
formation of the seed, often in response to environmental conditions.
Hormones also mediate endosperm dormancy: Endosperm in most seeds is
composed of living tissue that can actively respond to hormones
generated by the embryo. The endosperm often acts as a barrier to seed
germination, playing a part in seed coat dormancy or in the germination
process. Living cells respond to and also affect the ABA:GA ratio, and
mediate cellular sensitivity; GA thus increases the embryo growth
potential and can promote endosperm weakening. GA also affects both
ABA-independent and ABA-inhibiting processes within the endosperm.
Human use
Salicylic acid
Willow
bark has been used for centuries as a painkiller. The active ingredient
in willow bark that provides these effects is the hormone salicylic acid (SA). In 1899, the pharmaceutical company Bayer began marketing a derivative of SA as the drug aspirin.
In addition to its use as a painkiller, SA is also used in topical
treatments of several skin conditions, including acne, warts and
psoriasis. Another derivative of SA, sodium salicylate has been found to suppress proliferation of lymphoblastic leukemia, prostate, breast, and melanoma human cancer cells.
Jasmonic acid
Jasmonic acid (JA) can induce death in lymphoblastic leukemia cells. Methyl jasmonate (a derivative of JA, also found in plants) has been shown to inhibit proliferation in a number of cancer cell lines, although there is still debate over its use as an anti-cancer drug, due to its potential negative effects on healthy cells.
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