Submitted to: The Plant Cell
Publication Type: Abstract Only
Publication Acceptance Date: January 1, 2005
Publication Date: August 4, 2005
Citation: Kim, H.J., Triplett, B.A. Trancriptional regulation of genes involved in secondary-wall cellulose biosynthesis in cultured cotton fiber. The Plant Cell Wall Biosynthesis Conference. 2005. Available from: http://xyloglucan.prl.msu.edu/cgi-bin/meetingAbstratpub.firstname.lastname@example.org&order=1&1Name-Kim&1Name=Hee-Jin. Technical Abstract: During the transition from cell expansion to secondary wall thickening during cotton fiber development, the rate of cellulose biosynthesis rises nearly 100-fold. A similar increase in cellulose biosynthetic capacity occurs in fibers produced in vitro by ovule culture. Although the genes for the cellulose synthase catalytic subunit, CesA, were first described from cotton fiber, little is known about how CesA expression in is regulated. We have identified the group of cotton CesA genes that are expressed during cell elongation and another set of CesA genes that are expressed during secondary wall thickening. We investigated changes in culture conditions that alter the timing of secondary cell wall CesA expression using real-time quantitative RT-PCR Twenty-four hour treatment with exogenous indole acetic acid and/or abscisic acid at a time prior to initiation of secondary cell wall synthesis stimulated the premature expression of CesA1 and CesA2, genes responsible for secondary wall synthesis in cotton fiber. Simultaneous treatment with auxin and abscisic acid had an additive effect on relative transcript abundance for CesA1 and CesA2. Similar phytohormone treatments had little effect on the expression of genes predominantly expressed during cell elongation or constitutively expressed throughout fiber development (i.e. a-tubulin 4, a-tubulin 5, actin, expansin 1, and ubiquitin conjugating enzyme). Furthermore, addition of exogenous gibberellic acid, an essential phytohormone for fiber elongation, down-regulated expression of secondary wall CesA genes. Evidence for a similar pattern of phytohormone-mediated gene regulation of a cotton CesA promoter in transgenic Arabidopsis will be discussed with a model that integrates these results.