Abstract
In barley, there is a single recessive semi-dwarf gene, uzu, which shows a plant type similar to green revolution genes of rice and wheat. The green revolution caused by gibberellin-related mutations, but the uzu gene was known to be independent to GA. In this study, we comprehensively analyzed the uzu gene from both morphological and physiological aspects using uzu isogenic lines. We found that the uzu line showed the similar phenotype to rice brassinosteroid receptor gene mutant, d61: inhibited elongation of the second internode from top, insensitive to exogenous brassinolide and over-accumulation of endogenous brassinosteroids. We examined rice D61 homologous gene in barley and found a single nucleotide substitution in the kinase domain of the gene which led to an amino acid substitution. The mutation was mapped on the same position with uzu, then, we concluded that uzu caused by the mutation in barley brassinosteroid receptor gene.
