利用RIL群体比较定位糙米和精米蛋白质含量的QTL

Comparison of Quantitative Trait Loci Controlling the Protein Content of Brown and Milled Rice Using a Recombinant Inbred Line Population

稻米蛋白质含量是水稻(Oryzasativa L.)营养品质育种的重要内容之一。本研究以珍汕97与南洋占杂交构建的重组自交系(RIL)群体为材料,结合其建立了由190个SSR标记组成的遗传图谱,利用QTLmap-per1.6对糙米和精米中的蛋白质含量的遗传基础进行了分析,共定位到4个控制糙米含量的QTLs和2个控制精米含量的QTLs。其中,控制精米蛋白质含量的2个QTLs与控制糙米蛋白质含量的2个QTLs位置一致,这2个QTL(qpc1和qpc2)在糙米和精米的蛋白质含量中均解释了较大的表型变异,而且糙米和精米蛋白质含量的相关系数为0.814,这表明糙米和精米的蛋白质含量具有相似的遗传基础。研究还发现上位性在糙米和精米蛋白质含量的遗传中也起很重要的作用。其中,在糙米蛋白质含量中,上位性QTLs可以解释42.2%的表型变异;在精米蛋白质含量中,上位性QTLs共解释了27.8%的表型变异。本研究初步揭示了稻米蛋白质含量的遗传基础,为分子标记辅助选择改良稻米品质及蛋白质含量基因的克隆提供了有益的信息。

The improvement of grain quality, such as protein content （PC）, has been a major concern for rice （O- ryza sativa L.） breeding. In this study, a linkage map consisting of 190 SSR （Simple Sequence Repeat） markers was constructed, using a recombinant inbred line （RIL） population derived from the cross between Zhenshan 97 and Nanyangzhan. Based on the QTLmapper 1.6, six quantitative trait loci were detected, with two for the milled rice and four for the brown rice. The QTL （qpc） flanked by RM472 and RM104 on chromosome 1 was the largest one detected in both brown and milled rice, with the positive alleles from Zhenshan 97 allele. The other one （qpc2） in interval RM555-RM492 on chromosome 2 was also consistently identified in the two kinds of rice grains. These two consistent QTLs together explained considerable phenotypic variation, indicating a commonality in the genetic basis of brown and milled rice. A coincidence was found between these two QTLs and the loci involved in amino acid biosynthesis pathway. Our study shown that epistatic QTL can explain 27.78% of total phenotypic variation of protein content in milled rice and 42.1% in brown rice respectively, which indicated that epistatic QTL also plays an important role in protein content in rice. The results will be useful for marker-assisted selection in rice quality breeding programs, and for explaining the genetic basis of protein content in rice.