SPATIO-TEMPORAL ANALYSIS OF PHOTOTROPISM IN ARABIDOPSIS SEEDLINGS

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dc.contributor.advisorMurphy, Angus Sen_US
dc.contributor.authorPritchard, Candaceen_US
dc.contributor.departmentPlant Science and Landscape Architecture (PSLA)en_US
dc.contributor.publisherDigital Repository at the University of Marylanden_US
dc.contributor.publisherUniversity of Maryland (College Park, Md.)en_US
dc.date.accessioned2020-02-01T06:41:01Z
dc.date.available2020-02-01T06:41:01Z
dc.date.issued2019en_US
dc.description.abstractOptimization of light capture during seedling development is a major determinant of plant fitness. As seedlings emerge from the soil, the processes of photomorphogenesis and phototropism optimize deployment of structures that capture light for photosynthesis. Photomorphogenesis produces hypocotyl thickening, cotyledon expansion, and chloroplast maturation. Concurrent phototropic responses initiated by blue light position the expanding cotyledons to maximize photosynthesis. The mechanisms underlying both processes have been explored for more than 140 years, but are still not fully understood. This dissertation seeks to provide a better understanding of phototropism by exploring the timing and localization of the constituent mechanisms downstream of the well-characterized perception of blue light by the PHOTOTROPIN photoreceptors. The experiments described herein characterize temporally and spatially distinct processes involved in asymmetric auxin accumulations that lead to differential hypocotyl elongation. To better identify the link between early perception and later auxin transport and elongation events, an open-air system was used to remove seedling hindrance and provide better spatio-temporal resolution. These experiments confirmed the more rapid bending conferred by loss of the ATP Binding Cassette class B (ABCB) 19 auxin efflux transporter and loss of differential elongation in the mid hypocotyl elongation zone in higher order pinformed mutants. However, apart from the enhancement of phototropic bending observed in abcb19 and pin4 mutants, no auxin transport mutants tested showed alterations in early phototropic responses, and no mutant exhibited a delay in the onset of phototropic bending. Recently identified CBC1 and CBC2 (CONVERGENCE OF BLUE LIGHT (BL) AND CO2 1/2) have been shown to act in downstream signaling during phot1-mediated regulation of stomatal conductance. Similarly, during phototropism cbc1cbc2 double mutants show early defects in phot1-mediated phototropism. Further, CBC1 and CBC2 have been shown to regulate S-type anion channels. Analysis of S-type anion channel mutants also reveals defects in early bending responses. These results point to blue light-dependent regulation of anion channel activity having an important role during the earliest stages of phototropism.en_US
dc.identifierhttps://doi.org/10.13016/nzvf-m4cc
dc.identifier.urihttp://hdl.handle.net/1903/25452
dc.language.isoenen_US
dc.subject.pqcontrolledPlant sciencesen_US
dc.subject.pqcontrolledPhysiologyen_US
dc.subject.pqcontrolledDevelopmental biologyen_US
dc.subject.pquncontrolledarabidopsisen_US
dc.subject.pquncontrolledauxinen_US
dc.subject.pquncontrolleddevelopmenten_US
dc.subject.pquncontrolledphototropismen_US
dc.subject.pquncontrolledseedlingsen_US
dc.titleSPATIO-TEMPORAL ANALYSIS OF PHOTOTROPISM IN ARABIDOPSIS SEEDLINGSen_US
dc.typeDissertationen_US

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