The impact of phytochrome b silencing using rnai on some agronomic characters in arabidopsis thaliana

RNA interference (RNAi) is a powerful reverse genetic tool to study gene function by the interference with the gene activity. PHYB is the dominant phytochrome in light-grown plants, which plays an important role in plant development by the absorption of red (R) and far-red (FR) light and the transduction of intracellular signals during plant development. To construct transformation vectors that produce RNAs capable of duplex formation, gene-specific sequences (PHYB gene) in the sense and antisense orientations were linked and placed under the control of a strong viral promoter (35S). When introduced into the genome of Arabidopsis thaliana by Agrobacterium tumefaciens-mediated floral dipping transformation, double-stranded RNA expressing constructs corresponding to PHYB gene, caused specific and heritable genetic interference (efficiently knocked-down). It is shown that PHYB-RNAi transformed lines have significantly taller hypocotyls and larger leaf area compared with the NO.O wild plants. Reverse transcriptase-PCR (RT-PCR) revealed a correlation between the new PHYB-RNAi phenotypes and declining of normal PHYB-mRNA accumulation, suggesting that endogenous mRNA is the target of double-stranded RNA-mediated genetic interference. The ability to generate stably heritable RNAi and the resultant specific phenotypes allows to selectively reducing PHYB gene function in A. thaliana.