Molecular genetic study of cellulose biosynthesis mutant in Italian ryegrass

纤维素是家畜最重要的营养物质之一，近年来被公认为是生产生物乙醇的原料。为了揭示多年生黑麦草纤维素生物合成的机理，我们对多年生黑麦草脆性柱状突变系的饲料成分进行了分析，发现与正常系和品种相比，其纤维素含量较低，半纤维素含量较高。在突变体与正常单株杂交产生的F1群体中没有观察到脆性表型，而在与突变亲本回交的BC1F1群体中，脆性表型呈1：1分离，表明脆性表型受1个隐性遗传位点控制。对BC1F1群体进行的群体分离分析表明，在黑麦草连锁群4中选择了两个紧密连锁的SSR标记，这表明黑麦草的脆性遗传位点位于这两个SSR标记附近。

Cellulose is one of the most important nutrients for domestic ruminants and is recently recognized as a material for bio-ethanol production. To reveal a mechanism of the cellulose biosynthesis, we analyzed feed composition of a brittle column mutant line of Italian ryegrass and found its lower content of cellulose and higher content of hemicellulose when compared to those of normal lines and cultivars. The brittleness phenotype was not observed in an F1 population derived from a single cross between the mutant and a normal individual, but was segregated in a 1:1 ratio in a BC1F1 population derived from backcrossing the F1 progeny to the mutant parent, indicating that the brittleness phenotype is controlled by one recessive genetic locus. Bulked segregant analysis with the BC1F1 population selected two SSR markers that have been shown to tightly link together in ryegrass linkage group 4, suggesting that the genetic locus for the brittleness locates around the two SSR markers.