Development And Application Of The Key Enzyme Genes Sequence-tagged Molecular Markers Of Starch Biosynthesis In Rice (Oryza Sativa L.)

Rice quality refers to starch properties to a large degree, therefore improvement of starch properties is one of the most important goals in rice breeding. Starch is composed of amylose and amylopectin. The proportion of amylose against amylopectin and the fine structure of amylopectin determine rice quality jointly. Synthesis of amylose is directed by granule bound starch synthase which is mainly encoded by Wx gene. Although the genetic research is thoroughly understood at present, the relationship between Wx multi-allele gene and GC and GT of rice still needs more efforts. Besides the influence of various Wx genes on rice quality along with the serious problems such as how to apply molecular marker assisted breeding into rice is done and needs further study. Amylopectin is synthesed more complicatedly by soluble starch enzyme, soluble starch synthase and starch debranching enzyme. These enzymes compose of several isozymes. Little has been understood so far due to the complex synthesis of amylopectin. However with the sequence of rice genome in hand and the release of the whole genomic sequence of indica rice 93-11 and japonica rice Nipponbare, polymorphism region is obtained through sequence comparisons of corresponding genes in subspecies indica and japonica rice. Tags of these polymorphism sites play a crucial role in saturation genetic map, map-based cloning, gene function analysis and unveiling genetic polymorphism. Under such a background, the correlation between genetic polymorphism of rice Wx gene and major quality indexes AC, GC and GT of rice was conducted on one hand in this study. On the other hand, the relationship between genetic polymorphism of branching enzyme and debranching enzyme and physiochemical characteristics of rice starch was analyzed. Results in this study are covered in four points.1. Based upon data comparison between indica and japonica rice, 9 sequence-tag molecular markers were successfully constructed. Among them, AP1280-EcoRV was the tag of Agp gene, RB2504B, RB3174, RB3828 and RB10420-ACCâ…¡ were tags of Rbe1 gene, RB1062 and RB10637 were tags of Rbe3 gene, and Iso5980B and R114/113 were tags of Iso and Pul genes respectively.2. The materials were tested by the tags of branching enzyme gene to analyze the relation between genetic polymorphism of Rbe1 and Rbe3 genes and the rice starch characteristic. The result indicated that the inheritance of GT was probably related to genetic polymorphism locus of thetags of RB3828 and RB1062 , mainly affected by non-allele additive or interaction effect,furthermore the controlling genes of GT were probably related to the genetic polymorphism loca of RB3174 ;and that the inheritance of...