The role and control of growth suppression in the transition from diffuse to apical meristematic growth in Physcomitrella patens (Funariaceae).
Item
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Title
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The role and control of growth suppression in the transition from diffuse to apical meristematic growth in Physcomitrella patens (Funariaceae).
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Identifier
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AAI9997110
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identifier
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9997110
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Creator
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Mignone, Madeline Micceri.
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Contributor
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Adviser: Dominick V. Basile
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Date
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2001
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Language
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English
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Publisher
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City University of New York.
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Subject
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Health Sciences, Audiology | Biology, Plant Physiology
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Abstract
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"The Suppression Hypothesis", proposed by Basile and Basile states, in part, that the interrelated actions of auxin, ethylene, and hydroxyproline containing arabinogalactan proteins (AGPs) comprise a correlative control system involved with the place-dependent suppression of cell proliferation. They further proposed that this correlative control system plays three important roles in plant morphogenesis. Of the three roles, this study concentrated on the first, the mediation of the transition from diffuse to apical growth. Using Physcomitrella patens as a model system, it was ascertained that the hypothesized interrelated action of auxin, ethylene, and arabinogalactan proteins regulated the transition from a protonematal stage, characterized by a diffuse pattern of cell proliferation to a leafy gametophore stage, characterized by strictly apical growth. Antagonists of each component of the chemoregulatory system (i.e., auxin, ethylene, and hydroxyproline proteins[AGPs]) were used to determine whether each is involved in bringing about the changes from a primary chloronematal stage to that of the gametophore bud stage. 2-[(1-Naphthalenyl-amino)carbonyl]benzoic acid (ALANAP) and 2,3,5 triiodobenzoic acid (TIBA) were the antagonists used against auxin transport, aminoethoxyvinylglycine (AVG) as an antagonist to ethylene synthesis, and hydroxy-L-proline (Hyp) and 3,4 dehydroproline (3,4 D) as antagonists of hydroxyproline synthesis. When compared to the control, each of these antagonists successfully prevented the suppression of diffuse cell proliferation and thereby the transition from the chloronematal stage to the gametophore stage.;Comparative analysis of AGPs revealed significant differences in the quantity of protein extracted from equal amounts of diffusely growing protonema, desuppressed tissue and the apically grown leafy gametophore (suppressed) tissue. Electrophoretic studies also revealed a difference in the protein profile between the chloronematal and gametophore tissue.;That auxin and ethylene promote the transition was evidenced by the finding that 1-naphthaleneacetic acid-NAA (auxin) and or 1-aminocyclopropane-1 carboxylic acid-ACC (an ethylene precursor) accelerated the transition from protonernata to bud formation.;Further physiological studies provided evidence that the suppression of gametophytic tissue could be reversed by exogenous treatments of antagonists to auxin transport, ethylene production, and AGP synthesis (the same antagonists cited above). This indicates that the apical dominance countermanded, thus providing a reversion back to a desuppressed state.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
