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Hypocotyl directional growth in Arabidopsis: a complex trait

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Title Hypocotyl directional growth in Arabidopsis: a complex trait
 
Creator Gupta, Aditi
Singh, Manjul
Jones, Alan M.
Laxmi, Ashverya
 
Subject Arabidopsis
trait
Hypocotyl
 
Description The growth direction of the Arabidopsis (Arabidopsis thaliana) etiolated-seedling hypocotyl is a complex trait that is controlled by extrinsic signals such as gravity and touch as well as intrinsic signals such as hormones (brassinosteroid [BR], auxin, cytokinin, ethylene) and nutrient status (glucose [Glc], sucrose). We used a genetic approach to identify the signaling elements and their relationship underlying hypocotyl growth direction. BR randomizes etiolated-seedling growth by inhibiting negative gravitropism of the hypocotyls via modulating auxin homeostasis for which we designate as reset, not to be confused with the gravity set point angle. Cytokinin signaling antagonizes this BR reset of gravity sensing and/or tropism by affecting ethylene biosynthesis/signaling. Glc also antagonizes BR reset but acts independently of cytokinin and ethylene signaling pathways via inhibiting BR-regulated gene expression quantitatively and spatially, by altering protein degradation, and by antagonizing BR-induced changes in microtubule organization and cell patterning associated with hypocotyl agravitropism. This BR reset is reduced in the presence of the microtubule organization inhibitor oryzalin, suggesting a central role for cytoskeleton reorganization. A unifying and hierarchical model of Glc and hormone signaling interplay is proposed. The biological significance of BR-mediated changes in hypocotyl graviresponse lies in the fact that BR signaling sensitizes the dark-grown seedling hypocotyl to the presence of obstacles, overriding gravitropism, to enable efficient circumnavigation through soil.
 
Date 2014-05-09T06:40:30Z
2014-05-09T06:40:30Z
2012
5 June 2012
 
Type Article
 
Identifier Plant Physiol., 159(4): 1463-1476
http://hdl.handle.net/123456789/231
 
Language en
 
Publisher Am. Soc. of Plant Biologists