|MURAI, NORIMOTO - Louisiana State University|
Submitted to: Annual International Plant & Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: 11/5/2010
Publication Date: N/A
Interpretive Summary: The cotton fibers quality is directly affected by the production of a biopolymer called cellulose during cotton fiber development. Molecular mechanisms regulating cellulose production have not been well-characterized. To understand the regulation of cellulose production in cotton fibers, we examined which plant hormones can affect the expression levels of a gene named cellulose synthase catalytic subunit that is essentially responsible for cellulose production in fibers. Our results showed that one of plant hormones, auxin can not only regulate the expression levels of cellulose synthase, but also control a transition between cotton fiber elongation stage to cotton fiber cellulose thickening stage in cultured cotton fibers and other transgenic plants. Based on the results, it is proposed that auxin may play important roles in cellulose production during cotton fiber development. This information will help researchers to develop strategies for enhancing cellulose production in cotton fibers, and will ultimately contribute to improved cotton fiber quality. The data are also useful to plant cell wall researchers to understand cellulose production mechanisms for bioenergy production.
Technical Abstract: Cotton (Gossypium hirsutum L.) fibers are unicellular trichomes that differentiate from epidermal cells of developing cotton ovules. Mature fibers exhibit thickened secondary walls composed of nearly pure cellulose. Cotton fiber development is divided into four overlapping phases, 1) initiation stage, 2) primary cell wall (PCW) biosynthesis stage for fiber elongation, 3) secondary cell wall (SCW) cellulose biosynthesis stage for thickening cell wall, and 4) maturation stage. At the transition from PCW to SCW biosynthesis, most genes involved in SCW cellulose biosynthesis are up-regulated and the rate of cellulose synthesis in cotton fibers significantly increases. However, molecular mechanisms regulating the transition from PCW to SCW biosynthesis in developing cotton fibers have not been elucidated. To understand what triggers the onset of the transition from PCW to SCW in developing cotton fibers, we have studied phytohormonal effects on transcriptional regulations of genes involved in SCW cellulose biosynthesis using cultured cotton fibers and transgenic Arabidopsis. We have found that exogenous auxin treatment affected the expression levels of SCW genes in cultured cotton fibers as well as transgenic Arabidopsis, and regulated the timing of the transition from PCW to SCW in cultured cotton fibers. The results will be presented.