Poster: Signaling, cell-to-cell

Abs # 419: Role of Brassinosteroid in Cotton Fiber Development

Presenter:	Sun, Yan , yan.sun@ttu.edu
Authors	Sun, Yan  (A)   Abdel-Mageed, Haggag  (A)   Veerabomma, Suresh  (A)   Allen, Randy  (A)
Affiliations:	(A): Department of Biological Sciences, Texas Tech University

Of the various steroids that have been identified in plants, only brassinosteroids (BR) are found throughout the plant kingdom and, when applied exogenously, exert effects on plant growth and development. BR stimulates growth through enhanced cell division and cell elongation. The effects of exogenously applied BR on cotton fiber development in ovule cultures have been reported. Cotton ovule in vitro culture is an effective method to study the effects of BR and brassinazole (BRZ, a BR biosynthesis inhibitor) on cotton fiber development. Addition of 10 然 BRZ eliminates fibers from most parts of the ovule although some fibers remain near the funiculus. While higher concentrations of BRZ completely inhibit fiber development, they also inhibit growth of the ovule. Simultaneous addition of 10 然 BRZ and 0.1 然 brassinolide (BL) to the cultured ovules partially restores fiber development, indicating that the inhibition of fibers by BRZ is, at least for the most part, due to its inhibition of BR biosynthesis. Microscopic analysis clearly shows that fiber initiation and elongation are both inhibited by 10 然 BRZ, and can be subsequently restored by 0.1 然 BL. To study the effect of BRZ on gene expression, we analyzed GhBRI1 (cotton BR receptor) and KC22 (BR regulated XET) expression using quantitative real-time PCR. The results indicate that BR is a critical signaling factor regulates cotton fiber development.