The Source of genes related to rice grain starch synthesis among cultivated varieties and its contribution to quality

chinois. 明确高产水稻品种中与淀粉合成相关基因的性质，为稻米品质改良提供指导。以53个典型的籼粳品种和近年育成的高产水稻品种为材料，分析了供试品种的理化品质和RVA谱特征，并利用根据籼粳基因组序列差异设计的Wx、Sbe1、Sbe3基因的分子标记，检测了53个水稻品种的基因型，并分析了3个基因位点的遗传学效应。3个分子标记均能很好的区分3个位点上等位基因的籼粳来源，根据3个位点的基因型可将53个品种分为6种类型。单个基因遗传效应分析表明：在不同基因型品种间淀粉的理化特性（AC，GC, RVA）存在显著或极显著差异，3个基因的联合效应在不同基因型组合间也存在显著的差异。3个基因在高产品种培育过程中得到了广泛的交流和重组，而且3个基因位点上的不同等位基因（籼粳）对稻米淀粉的合成具有不同的遗传效应。其中Wx基因的影响是最主要的，Sbe1、Sbe3基因次之。3个基因位点的分子标记可为高产品种的品质改良提供快捷的工具。

anglais. The property of starch in rice grain endosperm is a very important determinant for rice quality, and it is essential to understand genetic effect of the genes related to starch synthesis in high-yielding rice varieties for rice quality improvement. The physico-chemical properties (e.g. amylose content, gel consistency and RVA profile) were assessed on 53 rice varieties, including some typical indica/japonica landraces and some high-yielding modern varieties. And molecular markers for Sbe1, Sbe3 developed based on sequence diversities between the rice subspecies indica and japonica, together with PCR-AccⅠ marker for Wx gene were used to investigate the genotypes of 53 rice cultivars. The result showed that the developed molecular markers for Wx, Sbe1, Sbe3 could distinguish indica or japonica alleles at three loci. Among all the 53 rice cultivars, six genotype combinations were observed at Sbe1, Sbe3 and Wx loci, while WxiSbe1jSbe3i and WxiSbe1jSbe3j genotype were absent. In order to explore the genetic effects of three genes, especially for starch branching enzyme genes, ANOVA and multiple comparison analysis were conducted. It showed that rice cultivars with different genotypes exhibited different phenotypes, including amylose content, gel consistency and some of RVA characteristics, and the significant differences were observed. It was concluded that these three genes had randomly recombined during the process of the rice variety development. And the genetic effects of indica and japonica alleles at three gene loci were different, of which, Wx gene plays a major role in determining the starch properties, followed by Sbe1 and Sbe3, and the genetic effects of Sbe1 and Sbe3 in different backgrounds (Wxi, Wxj) are different. The results have provided a clue for rice good quality variety development, and the molecular markers will benefit the rice quality improvement.