ARS | Publication request: PHYTOHORMONE REGULATION OF COTTON FIBER DEVELOPMENT IN VITRO

Submitted to: International Association for Plant Tissue Culture & Biotechnology Congress
Publication Type: Abstract
Publication Acceptance Date: June 15, 2006
Publication Date: August 13, 2006
Citation: Triplett, B.A., Kim, H., Hinchliffe, D.J., Sze, S., Thaxton, P., Stelly, D., Chen, J. 2006. Phytohormone regulation of cotton fiber development in vitro. Proceeding of the International Association for Plant Tissue Culture & Biotechnology Congress. 16.

Technical Abstract: Our team is interested in the regulation of two time points in cotton fiber development: initiation of fiber growth from ovule epidermal cells and the transition from fiber elongation to secondary wall biogenesis. These two developmental phases determine key properties of fiber quality and yield. Cotton ovules, excised from ovaries prior to fertilization, will continue development in vitro under defined conditions when auxin and gibberellic acid are present. By transcript profiling with oligo-microarrays we have begun to identify genes that are differentially regulated in cultures established with auxin and gibberellin compared to cultures where the phytohormones are absent. This approach will identify essential targets for increasing fiber number per seed, an important component of yield. After initiating growth, seed trichomes (fibers) elongate for about 13 days in culture and then begin producing thick, cellulosic secondary cell walls. A distinct set of cellulose synthase or beta-glucan synthase (CesA) genes are up-regulated during secondary wall biogenesis. We have investigated culture conditions for prematurely inducing CesA expression in vitro. Abscisic acid in combination with auxin is very effective in increasing transcript abundance of CesA genes as measured by quantitative, reverse transcription PCR. Gibberellic acid acts as an antagonist to abscisic acid activity in this assay. In silico analysis of cotton CesA promoters shows an abundance of phytohormone-responsive cis-acting elements. Analysis of cotton ovule cultures using contemporary techniques in plant molecular biology offers the potential for uncovering fundamental aspects of plant growth and development that will also be useful to for designing applied approaches for cotton improvement.