高粱籽粒单宁形成基因Tannin2的功能鉴定及遗传变异分析

高粱是重要的粮食作物，也是酿造、饲料和生物能源的原料。但是，高粱籽粒中富含单宁，影响籽粒品质及消化吸收，限制高粱作为食品及饲料的应用。因此，解析高粱籽粒单宁形成的遗传机制，选育不同单宁含量的高粱品种具有十分重要的意义。研究表明，高粱籽粒单宁形成由B1和B2两个基因位点互补控制。在我们前期已克隆Tannin1基因（B2）并鉴定了Tannin1内两个功能丧失功能性等位变异，初步确定B1位点的候选基因（Tannin2）的基础上，本研究拟进一步对Tannin2的功能进行鉴定；对不同单宁含量的高粱种质中Tannin2进行克隆、测序，明确Tannin2内的功能性等位变异类型及其在高粱种质中的分布；解析Tannin2与Tannin1互作控制单宁形成的遗传机制；开发可用于高通量标记辅助选择的诊断性标记，应用于高粱育种，降低高粱单宁含量，改善高粱饲用和加工品质。

Sorghum is an important food crop and also a raw material for brewing, feed and bioenergy. However, sorghum contains high condensed tannins in testa layer below the pericarp. Tannins impact grain quality and digestion, which limits the application of sorghum grains. Therefore, it is very important to uncover the genetic mechanism that control tannin presence in sorghum grains and develop sorghum varieties with different tannin content. Traditional genetic analysis showed that the presence of tannin in sorghum grains is controlled by two complementary dominant genes B1 and B2. In our previous study, Tannin1 (B2) was cloned and characterized and two loss-of-function alleles in Tannin1 were identified. The candidate gene of B1 was initially identified as Tannin2. In this study, the biosynthetic function of Tannin2 will be firstly characterized, and then cloned and sequenced in different varieties to dissect functional allelic variations and their distribution in sorghum germplasm. At the same time, the genetic mechanism underlying the interaction between Tannin1 and Tannin2 will be elucidated. Finally, diagnostic markers will be developed for high-throughput mark assisted selection in sorghum breeding to reduce sorghum tannin content and improve grain quality as feed and food.