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Maritimer
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copy paste notes from tonight's straw hat reading.
HORMONAL REGULATION O F DEVELOPMENTAL AND PHYSIOLOGICAL PROCESSES ... many—perhaps all—growth phenomena are the result of interaction and balance between several hormones,... (Kenneth Thimann, 1977, p . 203) All plant hormones have multiple roles i n plant growth o r defense, i.e. , they ar e pleiotropic in their effects. T o thi s basic theme, a layer o f complexity i s added b y th e fact that two o r more hormones bring about th e same, o r similar, responses. Fo r example, cell division i s mediated b y cytokinins (CKs), auxins, o r gibberellins (GAs). Cell enlargement involves action b y auxin, GA, brassinosteroids (BRs), o r ethylene. Abscisic acid (ABA), ethylene, an d jasmonates (JAs) ar e involved i n th e ability o f a plant to cope with biotic o r abiotic stresses. This redundancy i s a hallmark o f plant development, although i t i s no t clear whether i t i s real o r only apparent, i.e., tw o hormones regulate closely related bu t different aspects o f th e same process. Plant hormones also regulate some activities that ar e specific t o each hormone. Fo r instance, patterning i n embryo development an d polar phenomena such a s apical dominance, vascular differentiation, an d tropic growth under th e influence o f light o r gravity are principally regulated b y th e endogenous auxin, indoleacetic acid o r lAA; mobilization of seed food reserves i n cereal grains i s specific t o GAs; see d dormancy i s induced by ABA; fruit ripening i s associated with ethylene; an d JAs ar e uniquely involved in th e deposition o f vegetative storage proteins. The chapters i n Section II I o f this book reflect th e apparent redundancy and uniqueness of hormone action. They also show that even relatively simple processes. Plant hormones also regulate some activities that ar e specific t o each hormone. Fo r instance, patterning i n embryo development an d polar phenomena such a s apical dominance, vascular differentiation, an d tropic growth under th e influence o f light o r gravity are principally regulated b y th e endogenous auxin, indoleacetic acid o r lAA; mobilization of seed food reserves i n cereal grains i s specific t o GAs; see d dormancy i s induced by ABA; fruit ripening i s associated with ethylene; an d JAs ar e uniquely involved in th e deposition o f vegetative storage proteins.
The chapters i n Section II I o f this book reflect th e apparent redundancy and uniqueness of hormone action. They also show that even relatively simple processes. such as apical dominance o r production o f lateral roots, involve a n interaction o f tw o o r more hormones an d their relative levels, which ar e affected b y environmental and/or developmental cues. Such interaction i s often antagonistic, as , fo r example, lA A and C K interaction in lateral root formation, although i t i s no t clear whether such antagonism i s used for regulation o f th e process i n nature. Synergistic interaction also occurs, e.g., fo r ethylene and J A i n induction o f some genes i n plant defense against pathogens. Finally, several hormones may ac t i n concert, on e after another, t o regulate a sequence o f developmental events. Fo r example, fruit se t may b e regulated b y lAA, fruit growth by GA, fruit ripening b y ethylene, an d seed maturation an d dormancy b y ABA. Because of these interactions among homones and between hormones and environmental factors, the extent o f which we have only recently begun t o appreciate, a n understanding of plant hormonal response i s a complex and difficult fabric t o unentangle.
In the past, plant hormones have been credited with a bewildering array o f responses—there is hardly any plant process that ha s no t been attributed t o one o r another hormone. Such conclusions were often drawn from treatment o f whole plant o r isolated organs/tissues with exogenous hormones, often a t unnaturally high concentrations. These treatments disturb th e natural homeostasis and generally d o not provide a true indication o f th e role o f a hormone. That rol e i s deciphered better by the us e o f mutants that ar e deficient i n o r ar e insensitive t o a specific hormone o r b y a defined biochemical response t o a hormone. Fo r thi s reason, no t al l responses attributed to hormones ar e covered i n these chapters; rather th e chapters ar e selective i n that they deal with only th e better understood and, hopefully, major responses an d processes.
Fruit an d seed development and seed germination, covered i n Chapters 17, IS, and 19 , ar e growth-related processes in which CKs, lAA, an d GAs play important although still little understood roles, whereas fruit ripening an d seed maturation and dormancy ar e culminating phases o f growth, akin t o senescence, an d ar e regulated b y ethylene, ABA, an d possibly J As.
Thimann, K. V . (1997). "Hormone Action i n th e Whole Life o f Plants." Th e University o f Massachusetts Press, Amherst.
Wow,
I would like a copy of this book down in the office. Wonder if my Land of Lincoln library card can summon a borrowed copy?
HORMONAL REGULATION O F DEVELOPMENTAL AND PHYSIOLOGICAL PROCESSES ... many—perhaps all—growth phenomena are the result of interaction and balance between several hormones,... (Kenneth Thimann, 1977, p . 203) All plant hormones have multiple roles i n plant growth o r defense, i.e. , they ar e pleiotropic in their effects. T o thi s basic theme, a layer o f complexity i s added b y th e fact that two o r more hormones bring about th e same, o r similar, responses. Fo r example, cell division i s mediated b y cytokinins (CKs), auxins, o r gibberellins (GAs). Cell enlargement involves action b y auxin, GA, brassinosteroids (BRs), o r ethylene. Abscisic acid (ABA), ethylene, an d jasmonates (JAs) ar e involved i n th e ability o f a plant to cope with biotic o r abiotic stresses. This redundancy i s a hallmark o f plant development, although i t i s no t clear whether i t i s real o r only apparent, i.e., tw o hormones regulate closely related bu t different aspects o f th e same process. Plant hormones also regulate some activities that ar e specific t o each hormone. Fo r instance, patterning i n embryo development an d polar phenomena such a s apical dominance, vascular differentiation, an d tropic growth under th e influence o f light o r gravity are principally regulated b y th e endogenous auxin, indoleacetic acid o r lAA; mobilization of seed food reserves i n cereal grains i s specific t o GAs; see d dormancy i s induced by ABA; fruit ripening i s associated with ethylene; an d JAs ar e uniquely involved in th e deposition o f vegetative storage proteins. The chapters i n Section II I o f this book reflect th e apparent redundancy and uniqueness of hormone action. They also show that even relatively simple processes. Plant hormones also regulate some activities that ar e specific t o each hormone. Fo r instance, patterning i n embryo development an d polar phenomena such a s apical dominance, vascular differentiation, an d tropic growth under th e influence o f light o r gravity are principally regulated b y th e endogenous auxin, indoleacetic acid o r lAA; mobilization of seed food reserves i n cereal grains i s specific t o GAs; see d dormancy i s induced by ABA; fruit ripening i s associated with ethylene; an d JAs ar e uniquely involved in th e deposition o f vegetative storage proteins.
The chapters i n Section II I o f this book reflect th e apparent redundancy and uniqueness of hormone action. They also show that even relatively simple processes. such as apical dominance o r production o f lateral roots, involve a n interaction o f tw o o r more hormones an d their relative levels, which ar e affected b y environmental and/or developmental cues. Such interaction i s often antagonistic, as , fo r example, lA A and C K interaction in lateral root formation, although i t i s no t clear whether such antagonism i s used for regulation o f th e process i n nature. Synergistic interaction also occurs, e.g., fo r ethylene and J A i n induction o f some genes i n plant defense against pathogens. Finally, several hormones may ac t i n concert, on e after another, t o regulate a sequence o f developmental events. Fo r example, fruit se t may b e regulated b y lAA, fruit growth by GA, fruit ripening b y ethylene, an d seed maturation an d dormancy b y ABA. Because of these interactions among homones and between hormones and environmental factors, the extent o f which we have only recently begun t o appreciate, a n understanding of plant hormonal response i s a complex and difficult fabric t o unentangle.
In the past, plant hormones have been credited with a bewildering array o f responses—there is hardly any plant process that ha s no t been attributed t o one o r another hormone. Such conclusions were often drawn from treatment o f whole plant o r isolated organs/tissues with exogenous hormones, often a t unnaturally high concentrations. These treatments disturb th e natural homeostasis and generally d o not provide a true indication o f th e role o f a hormone. That rol e i s deciphered better by the us e o f mutants that ar e deficient i n o r ar e insensitive t o a specific hormone o r b y a defined biochemical response t o a hormone. Fo r thi s reason, no t al l responses attributed to hormones ar e covered i n these chapters; rather th e chapters ar e selective i n that they deal with only th e better understood and, hopefully, major responses an d processes.
Fruit an d seed development and seed germination, covered i n Chapters 17, IS, and 19 , ar e growth-related processes in which CKs, lAA, an d GAs play important although still little understood roles, whereas fruit ripening an d seed maturation and dormancy ar e culminating phases o f growth, akin t o senescence, an d ar e regulated b y ethylene, ABA, an d possibly J As.
Thimann, K. V . (1997). "Hormone Action i n th e Whole Life o f Plants." Th e University o f Massachusetts Press, Amherst.
Wow,
I would like a copy of this book down in the office. Wonder if my Land of Lincoln library card can summon a borrowed copy?
He thinks I should tinker with this stuff verses ABA in our efforts to trigger enhanced glandular production thru hormonal stimulation. The vendor alludes to a 99% increase in trichome production. I am more excited about this prospect the more I learn reading.
