Molecular studies of enhanced apical dominance of phytochrome B mutant sorghum

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dc.contributor.advisor Finlayson , Scott A en_US
dc.contributor.committeeMember Burson , Byron L . en_US
dc.creator Kebrom , Tesfamichael Hintsa en_US
dc.date.accessioned 2010 -01 -14T23 :55 :33Z
dc.date.accessioned 2014 -02 -19T19 :38 :16Z
dc.date.available 2010 -01 -14T23 :55 :33Z
dc.date.available 2014 -02 -19T19 :38 :16Z
dc.date.created 2006 -12 en_US
dc.date.issued 2009 -05 -15 en_US
dc.identifier.uri http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1668
dc.description.abstract Light is one of the environmental signals that regulate axillary shoot development . However , little is known about molecular and physiological mechanisms regulating the development of the axillary shoot in response to light signals . Molecular events associated with the enhanced apical dominance of phytochrome B mutant sorghum (Sorghum bicolor ) were analyzed to reveal processes mediating axillary shoot development in response to light . The enhanced apical dominance of phyB -1 mutant sorghum is due to inhibition of bud outgrowth and is accompanied by upregulation of the dormancy -associated gene (SbDRM1 ) in the buds . Increased expression of the Teosinte Branched1 (SbTB1 ) gene (encoding a putative transcription factor that represses bud outgrowth ) suggests that the inhibition of bud outgrowth in phyB -1 sorghum is due to the absence of active phyB to repress SbTB1 . The results were confirmed by growing wild type seedlings at high plant density or with supplemental farred (FR ) light that induces enhanced apical dominance . However , the SbTB1 gene is not involved in the inhibition of bud outgrowth induced by defoliation in wild type seedlings . The results indicate variations in molecular mechanisms among different signals inhibiting branching . Increased expression of SbMAX2 (which encodes an F -box protein that represses bud outgrowth ) in buds repressed by light and defoliation suggests common mechanisms at the downstream end of pathways inhibiting branching . The expression levels of several cell cycle -related genes including SbPCNA , SbHis4 , SbCycD2 , SbCycB and SbCDKB were down -regulated in the repressed buds of FRtreated and defoliated seedlings indicating the suspension of cell division in those buds . However , these cell cycle -related genes were continuously expressed in the repressed buds of phyB -1 , suggesting that inhibition of bud outgrowth in phyB -1 is not associated with down -regulation of cell cycle -related gene expression . The down -regulation of cell cycle -related genes in the buds of FR -treated wild type seedlings indicates that other sensors , in addition to phyB , regulate bud outgrowth in response to FR enrichment . The approaches used and results achieved will provide direction for future research on this important topic . en_US
dc.format.medium electronic en_US
dc.format.mimetype application /pdf en_US
dc.language.iso en _US en_US
dc.subject apical dominance en_US
dc.title Molecular studies of enhanced apical dominance of phytochrome B mutant sorghum en_US
dc.type Book en
dc.type.genre Electronic Dissertation en_US
dc.type.material text en_US
dc.format.digitalOrigin born digital en_US

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Molecular studies of enhanced apical dominance of phytochrome B mutant sorghum. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1668 .

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