Abstract: A rice sheath blight resistance QTL qSB7(superscript Tq) on rice chromosome 7 of Teqing was confirmed by using the backcross between Teqing and Lemont. The effects and pyramiding effects of qSB7(superscript Tq), qSB9(superscript Tq) (a rice sheath blight resistance QTL mapped on chromosome 9 of Teqing) and qSB11(superscript Le) (a rice sheath blight resistance QTL mapped on chromosome 11 of Lemont) were studied by using a set of near-isogenic lines (NILs) under the background of Lemont. The results indicated that the three resistance QTLs could significantly improve the resistance to rice sheath blight separately or jointly. However. there might exist certain negative interactions among these three resistance QTLs. The importance of a uniform genetic background for studying QTL, and the significance of pyramiding and interacting effects among different QTLs in rice breeding were discussed.

Key words: Oryza sativa, sheath blight, resistance, quantitative trait locus, gene pyramiding, near-isogenic line

摘要： 利用特青/Lemont组合的回交群体，证实了特青第7染色体上存在抗纹枯病QTL qSB7Tq。以Lemont为轮回亲本，通过分子标记辅助连续回交结合性状鉴定，构建了qSB7Tq与另外两个抗水稻纹枯病QTL qSB9Tq（位于特青第9染色体）和qSB11Le（位于Lemont第11染色体）的一套近等基因系，对各抗性QTL的单个效应及其聚合效应进行了研究。3个抗性QTL单独存在或在聚合状态下均能显著提高水稻品种对纹枯病的抗性水平。但是，不同抗性QTL之间可能普遍存在一定的负向互作关系。讨论了一致的遗传背景对QTL研究的重要性，以及不同QTL的聚合效应及互作关系对育种实践的意义。

关键词: 水稻, 纹枯病, 抗性, 数量性状座位, 基因聚合, 近等基因系