The role of suppression in the morphogenesis and phylogeny of Streptocarpus prolixus (Gesneriaceae).
Item
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Title
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The role of suppression in the morphogenesis and phylogeny of Streptocarpus prolixus (Gesneriaceae).
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Identifier
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AAI3008864
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identifier
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3008864
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Creator
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Rauh, Richard Adolph.
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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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Biology, Botany
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Abstract
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Genetic controls ultimately determine the suppression of proliferation that in turn determine the size and shape of any particular species. The implementation of these controls, however, depends on a complex series of interrelated pathways largely epigenetic in nature. The hypothesis that auxin, ethylene, and some hydroxyproline-containing proteins play decisive roles in this implementation has been tested in lower plants. Here we extend this testing to a flowering plant. Antagonists of the action or synthesis of auxin, ethylene, and hydroxyproline-containing proteins, are applied exogenously to the seeds and seedlings of Streptocarpus prolixus C. B. Clarke.;The beta-glucosyl Yariv phenylglycoside (beta-D-Glc) 3 is known to selectively bind to that class of cell-surface associated proteins known as arabinogalactan-proteins (AGPs). Seeds and seedlings of S. prolixus were treated with (beta-D-Glc) 3 and alpha-galactosyl Yariv phenylglycoside (alpha-D-Gal) 3, which does not bind AGPs. With the exception of (alpha- D-Gal)3, the antimetabolites all induced similar morphological variations. They were, anisocotyly with a secondary phyllomorph, multiple phyllomorphs, anisocotyly with plumular growth, or isocotyly with plumular growth. All the variations appear related to the relative differences in time and degree of suppression of cells comprising the primary embryonic shoot meristems. The induced phenovariants copied the growth patterns of mature plants of other species in its subgenus (Streptocarpus). More remarkably, they also phenocopied morphotypes of species in a different subgenus (Streptocarpella), and the subfamily (Gesnerioideae) of the Gesneriaceae. The finding that the range and types of phenovariants induced by Hyp-protein antagonists are the same as those induced by a reagent that specifically perturbs AGPs strongly suggests that the Hyp-proteins mediating the pattern changes are hydroxyproline-containing AGPs. By extrapolation, because the induced phenovariation was due to the suppression of leaf and shoot development in S. prolixus and several leafy liverworts, these results support the hypothesis that certain AGPs can mediate the suppression of cell proliferation in organ primordia. The similar results produced lead to the conclusion that the same factors mediating place-dependent suppression in leafy liverwort gametophytes appear to perform the same function in flowering plant sporophytes. The results suggest that the molecular basis for the correlative inhibition of localized growth processes may be the same for all land plants.
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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.
