Genetic analysis and mapping with SSR markers of the brown midrib gene bmr-6 in Sorghum bicolor.

The mutants,which produced brown leaf midribs,reduced the content of lignin by 40% to 60% compared with normal varieties.This low lignin content largely promoted the rate of digestion in livestock.The F2 population was constructed from the hybrid of N592(bmr-6)and Sa(white midrib)to map the bmr-6 gene. The ratio of white and brown midribs was 3to 1in the F2 population.Therefore,the bmr-6 gene is a single recessive gene.Using 171 SSR markers and F2recessive population,one SSR(simple sequence repeats)marker (txp295)that linked with the bmr-6gene was detected and the genetic distance was 4.2cM.In addition,the bmr-6gene was mapped to the seventh linkage group of sorghum because the txp295 marker was located on this linkage group.