W207 GhHOX3 in Cotton Fiber Elongation

Date: Sunday, January 15, 2012
Time: 3:50 PM
Room: Pacific Salon 3
Chun-Min Shan , Shanghai Institute of Plant Physiology and Ecology, Shanghai, China
Chang-Qing Yang , Shanghai Institute of Plant Physiology and Ecology, Shanghai, China
Lingjian Wang , Shanghai Institute of Plant Physiology and Ecology, Shanghai, China
Xiao-Ya Chen , Shanghai Institute of Plant Physiology and Ecology, Shanghai, China
It has been proposed that cotton fiber and Arabidopsis leaf trichomes share common regulatory mechanisms. Compared to the well-established model of the trichome development in Arabidopsis, our knowledge of the regulation of cotton fiber development is still primitive. The Arabidopsis HD-ZIP IV transcription factor GL2 is a positive regulator working downstream of the GL1/GL3/EGL3/TTG1 core complex in trichome development pathway. We have analyzed the cotton GL1-like R2R3 MYB transcription factor GhMYB2 and three Gl2-like HOX factors (HOX1 to HOX3).  Analyses of expression patterns showed that GhHOX3 was highly expressed in rapidly elongating fiber cells. Surprisingly, a number of the 35S::GhHOX3 transgenic cotton lines were hampered in fiber elongation because of the co-suppression. Further quantitative RT-PCR showed that fiber length was correlated to GhHOX3 gene expression level. Expression of two cell wall protein genes were shown to be regulated by GhHOX3, and these wall proteins play an important role in promoting fiber growth. To further elucidate the functional roles of GhHOX3 in fiber development, we explored the expression profiles of 35S::GhHOX3 co-suppression line by Digital Gene Expression Tag Profiling (DGE) analysis. One hundred and thirty genes were up-regulated and 258 genes were down-regulated in the co-suppression line. The majority of differential expressed genes are potentially involved in biological processes related to fiber development, including transcriptional regulation, signaling transduction and metabolism. These data suggest that GhHOX3 plays an important role in the fiber elongation.