Positional cloning of rice BC3 : a causal gene of a secondary cell wall synthesis mutant "brittle culm" bc3

Abstract

Brittle culm mutants are known in rice and barley, and causes of their phenotypes are possibly due to defects in genes involved in secondary wall construction or its regulation. Cellulose content in the culm of bc3 mutant was reduced to about 3/4 compared to the wild type. By analyzing 697 F2 and F3 recessive plants derived from a cross between japonica strain M11 (bc3 mutant) and indica cultivar Kasalath, bc3 was narrowed down to a 94 kb region on chromosome 2. Complementation test of this region using originally developed pBIGRZ binary vector revealed BC3 to be a member of a big gene family, although its participation in wall construction had never been reported. Deletion of 156bp was detected in an important domain of this gene in the allele of M11. We will discuss the role of BC3 from the already known functions of this gene family in eukaryotes.