水稻单片段替换系群体的建立及QTL分析

Development of Single Segment Substitution lines(SSSLs)and QTL Analysis in Rice(Oryza sativa L.)

农作物大多数性状都是由多基因控制的数量性状 ,对数量性状基因座 (quantitativetraitloci,QTL)进行鉴定和定位对作物遗传育种具有重要意义。单片段替换系 (singlesegmentsubstitutionlines ,SSSL)消除了遗传背景的干扰 ,是用于QTL分析的重要试验材料。本研究以 6个水稻品种为供体 ,利用回交和微卫星标记辅助选择相结合的方法 ,建立了以华粳籼 74为遗传背景的水稻单片段替换系群体 ,并选用其中的 5 9个单片段替换系对水稻 2 4个重要农艺性状的QTL进行了鉴定 ;还利用一个单片段替换系的次级分离群体对抽穗期基因Hd - 3- 1进行了定位。主要试验结果如下 :1对供体亲本苏御糯、IR6 4、IRAT2 6 1、成龙水晶米、Lemont和IAPAR9与华粳籼 74之间的微卫星标记多态性进行了检测 ,6个供体亲本与华粳籼 74之间的多态率分别为 5 6 33%、 34 93%、 5 9 31%、33 19%、 5 5 90 %和 5 6 5 5 %。2对回交的遗传效应进行了分析 ,在BC2 F1和BC3F1单株中检出替换片段的平均数分别为 8 93个和4 37个 ,在BC2 F1和BC3F1单株中检出替换片段的平均长度分别为 32 2 3cM和 2 7 6 3cM ,BC2 F1和BC3F1受体亲本基因组的回复率分别为 81 5 5 %和 92 32 %。3建立了 118个以华粳籼 74为遗传背景的单片段替换系 ,其中包括

Most traits for crop breeding are quantitative in nature, which are controlled by polygenes. It is very important for crop improvement to accurately identify and finely map quantitative trait loci (QTLs). Single segment substitution lines (SSSL) containing only one segment of donor chromosome introgressed into a recipient genetic background permits QTLs to be mapped with greater precision. The present research have developed a single segment substitution line population which was in an elite genetic background of Huajingxian-74 (HJX-74) introgressed from 6 rice species using backcross and SSR marker assisted selection. We have identified the QTLs for 24 agriculturally important traits in 59 SSSLs, and mapped Hd-3-1 , a completely dominant gene for early heading date. The main results are as follows: 1 The microsatellite marker polymorphism between Suoyunuo, IR64, IRAT261, Chenglongshuijingmi, Lemont, IAPAR9 and HJX-74 were detected, the polymorphism between every donor parent with HJX-74 is 56 33%, 34 93%, 59 31%, 33 19%, 55 90% and 56 55%, respectively. 2 The genetic effects of backcross were analyzed. The average substitution in every BC 2F 1 and BC 3F 1 plant is 8 93 and 4 37, the average length of every substitution in BC 2F 1 and BC 3F 1 plant is 32 23cM and 27 63cM and the recovery rate of recipient genome in every BC 2F 1 and BC 3F 1 plant is 87 5% and 93 75%, respectively. 3 One hundred and eighteen overlapping single segment substitution lines with the HJX-74 genetic background have been developed, which include 86 different SSSLs. The SSSLs were distributed on 12 rice chromosomes and highest number (16) of SSSL were on chromosome 10. The average length of substituted segment in every SSSL is 23 0 cM All the SSSLs provide coverage of 57 11% of the rice genome. 4 Two hundred and forty eight QTLs for 24 agriculturally important traits in 59 SSSLs have been detected through t test (p≤0 001) between the SSSL and the recipient parent, These include 25 QTLs for heading date, 13 QTLs for neck length, 1 QTL for number of panicles, 16 QTLs for plant height, 5 QTLs for panicle length?7 QTLs for length of top most internode, 8 QTLs for length of top second internode, 4 QTLs for length of top third internode, 7 QTLs for length of top forth internode, 12 QTLs for flag leaf length, 22 QTLs for flag leaf width, 13 QTLs for length of top second leave, 14 QTLs for width of top second leave, 4 QTLs for length of top third leave, 12 QTLs for width of top third leave, 14QTLs for number of primary branches per panicle, 2 QTLs for number of secondary branches per panicle, 5 QTLs for number of grains per panicle, 10 QTLs for percent seed set, 6 QTLs for spikelet setting density, 11 QTLs for grain length, 13 QTLs for grain width, 11 QTLs for the ratio of grain length to width and 13 QTLs for grain weight. 5 Substitution mapping technology has been used to map some QTLs and twenty two QTLs have been mapped at less than 10 cM. 6 Hd-3-1 , a completely dominant gene for early heading date, has been segregated as a mendelian factor in a secondary segregation population of a SSSL. The mapping results showed that Hd-3-1 was located between microsatellite marker PSM304 and RM569 on the short arm end of Chromosome 3 at 2 4cM and 5 1cM from PSM304 and RM569, respectively. The genetic distances from Hd-3-1 to three another SSR markers, PSM305, PSM306 and RM231 were 2 7cM, 3 3cM and 8 9cM, respectively. From the above mentioned endeavor, the trail technology system of SSSL development and QTL identification has been established, which provide new idea and pathway of applying molecular marker technology to crop improvement.