Down-Regulation of the Brassinosteroid Receptor Gene, BRI1 in Creeping Bentgrass Results in a Dwarf Phenotype and Increased Drought Tolerance.

In plants, the most effective RNA interference (RNAi) strategy is to use long hairpin RNA (lhRNA) constructs containing inverted repeats (IRs), which is processed by the RNAi machinery into small interfering RNA (SiRNA) that silence target genes based on sequence homology. We generated RNAi knockdown mutants for the putative brassinosteroid receptor gene, BRI1 in creeping bentgrass through Agrobacterium-mediated transformation. The expression level of the endogenous BRI gene was significantly reduced in transgenic mutants. In addition, the mutants exhibited an extremely dwarf phenotype with reduced leaf length and width, shorter internodes, increased shoot density and reduced sensitivity to brassinosteroid. Furthermore, increased drought tolerance was observed in the knockdown mutants.