利用品质性状的回交选择导入系挖掘水稻抗纹枯病QTL

将优质、抗纹枯病的高秆供体Tarom Molaii和Binam导入半矮秆IR64和特青背景，培育品质性状回交选择构建的4个导入系群体IR64/Tarom Molaii、特青/Tarom Molaii、IR64/Binam和特青/Binam，定位了影响水稻抗纹枯病病级(disease scale, DS)、相对病斑高度(relative lesion height, RH)和株高(plant height, PH)的QTL。结果表明，4个导入系群体的DS与RH高度相关，两者与PH呈显著负相关。导入系后代各性状均呈现超亲分离，出现抗性明显优于双亲的抗病个体，其中40%左右属半矮秆抗病类型。采用单向方差分析，在这4个群体中分别定位到10、8、8和6个影响3个性状的QTL，多数基因座上降低DS和RH即增强抗病性同时增加株高的等位基因均来自两个供体。未在同一供体两个不同背景下检测到影响3个性状的相同QTL，表明抗纹枯病QTL表达有明显的遗传背景效应。PH与DS及PH与RH被定位在同一个显著标记位点的QTL数分别占两个性状QTL总数的38%和52%，表明水稻纹枯病抗性与株高关系密切，两者存在许多连锁位点。与以往相同群体品质性状QTL的定位结果相比，发现品质性状QTL与抗纹枯病QTL大多分布在染色体的不同区域，彼此独立遗传。对利用目标性状选择导入系定位非目标性状QTL的效果、影响因素及育种应用进行了探讨，强调了目标性状选择导入系对非目标性状QTL发掘及育种应用的重要性。

QTL Mining for Sheath Blight Resistance Using the Backcross Selected Introgression Lines for Grain Quality in Rice

QTLs for disease scale (DS), relative lesion height (RH) and plant height (PH) were mapped using the four introgression lines selected against grain quality from the four introgression populations between two elite varieties, IR64 and Teqing as recurrent parents and two tall varieties, Tarom Molaii and Binam with high grain quality and sheath blight resistance (SBR) as donors. DS had high significant positive correlation with RH, and both of them were significantly negatively correlated with PH. DS, RH and PH presented wide segregations even in the relative small (28–60) introgression populations, including some semidwarf plants segregated with overparent SBR. Ten, eight, eight and six QTLs for the three traits were identified in IR64/Tarom Molaii, Teqing/Tarom molaii, IR64/Binam and Teqing/Binam, respectively by one way ANOVA analysis. The two donor alleles at most QTLs reduced DS and RH as well as increased PH. No any a common QTL for each of the three traits was detected in the populations of the same donor in the two different background, indicating there was a obvious genetic background effect on expression of SBR- and PH-QTLs. QTLs linked to the same marker loci between PH and DS, and PH and RH accounted for 38% and 52% of total QTLs for the two traits, respectively, indicating SBR had tight relationship with PH and both of them shared some linked loci. As compared with the previous QTL mapping results of grain quality in the same populations, most QTLs for grain quality and SBR distributed in different chromosome regions and showed independently inherited. Efficiency, influencing factors and its application in breeding of QTL mapping for non-target traits using introgression lines selected against the target trait were deeply discussed, and importance of selective introgression lines in QTL mining and breeding use was also emphasized.