Characterization of CYP90B1/DWARF4 homolog in rice

Abstract

CYP90B1/DWARF4 catalyzes C-22 hydroxylation, the rate-limiting step of brassinosteroid (BR) biosynthesis in Arabidopsis. We have previously reported a rice CYP90B1/DWARF4 homolog, OsDWARF4, and its loss-of-function mutant, osdwarf4-1. The phenotype of osdwarf4-1 suggests that at least one functionally redundant gene is existed in the rice genome. A OsDWARF4-like gene identified by database screening is identical to CYP724B1/D11, which was recently identified as the gene corresponds to rice semi-dwarf mutant, d11. Because d11 was also showed mild phenotype similar to osdwarf4-1, we suspected that OsDWARF4 and CYP724B1/D11 function redundantly in rice. In the present study, we generated and characterized the osdwarf4-1 d11 double mutant. Based on these experiments, we will discuss the biological function of OsDWARF4 and CYP724B1/D11 in BR biosynthesis.