Identification of a Novel Cytochrome P450 Gene, Which Regulates Seed Length in Rice

Abstract

We have investigated the mechanism of regulation of seed length in rice. The rice d11 fruits small grain seeds and shows dwarfism with extremely short of second-internode. We isolated the D11 gene by map-based cloning method. The D11 gene seemed to encode a novel cytochrome P450. By BLAST searches, the deduced amino acid sequence of D11 gene showed high similarity to Arabidopsis DWF4 (43% of identity and 62% similarity). The accumulation of D11 mRNA was much more in the d11 mutant than in wild-type plants. We also studied the effect of BL on the expression of D11 mRNA, because the transcription of cytochrome P450s involved in BR biosynthesis are reported to be regulated in a feedback manner by the end product of BR-biosynthetic pathway, BL. The expression of D11 mRNA in the mutant was dramatically reduced with exogenously supplied BL.