Functional Identification And Analysis Of WOX Homeobox Genes In Rice Development

WOX(WUSCHEL-related homeobox) genes, as transcription factors genes, specifically express in plants. They are known to play vital roles in regulating the development of plant tissues and organs in dicots model plant Arabidopsis thaliana, For example, involving in early embryo differentiation, stem cell stabilization and maintenance, procambium, leaf and ovary development. Recently, functions of WOX genes in tomato, Confiers, Sorghum and Maize have been reported, and these results suggest that WOX genes also are involed in key development processes. However, rice, as the most important food crop in the world and the monocot model plant, WOX genes functions are poorly investigated. In this study, We systematically analysed the functions of WOX genes during rice development and abiotic stresses through affymetrix microarray data of WOX genes in rice genome in different organs and tissues including eight vegetative tissues such as seeds after imbibition, radicle, root, leaf and eight reproductive tissues like panicle, floral and endosperm and combined with transgenetic technology. It revealed some mechanism of WOX genes involed in rice development, the main results as follow:1. Affymetrix microarray data analysis of eleven WOX genes in rice genome in different organs and tissues indicated that these genes were participated in rice overall development processes and exhibitting obvious tissues/organs-specific.2. Quantitative realtime PCR and in situ hybridization further suggest that OsWOX4、OsWOX5、OsWOX9A and OsWOX12 B were involved in embryogenesis and floral organ development.3. Numerous cis-acting elements related to plant hormone including auxin, cytokin, gibberin, abscsic acid were found to exist in the promoter regions of WOX genes. Meanwhile, the results of quantitative realtime PCR also showed that the mRNA transcriptional level of WOX genes were rapidly induced by plant hormone and abiotic stress treatments. These results further suggested rice WOX genes may also associated different environment responses. 4. Transgenetic plant of OsWOX4 RNAi exihibited lots of defected development, for instance, dwarf phenotype, small and narrow flag leaf, abnormal panicle and embyo development. These findings and expression profile data demonstrated that OsWOX4 is involed in multipled aspects of rice development.5. Seventeen proteins interacted with Os WOX12 A were screened in rice root by yeast two hybrid. Furthermore, their expression patterns in root were analyzed subsequently. This rsults will provide important clues for OsWOX12 A function in rice crown root formation.All these results suggested that rice WOX genes play important roles during rice development processes, and they are also involved in plant hormone and abiotic stress responses. These results presented here will further provide insight in understanding the functions of WOX genes in rice development, hormone signaling, and abiotic stress responses.