【摘要】 利用水稻纹枯病菌强致病菌系RH-9人工接种Lemont导入到特青背景的213个近等基因导入系(TQ-ILs)群体和特青导入到Lemont背景的195个近等基因导入系(LT-ILs)群体,定位和分析了水稻抗纹枯病数量性状座位(QTL)及其表达的环境与遗传背景效应。亲本Lemont对RH-9表现为高度感病,特青表现为中等抗病。人工接种后TQ-ILs群体的相对病斑高度(病斑高度与株高比)呈连续正态分布,LT-IL群体则明显偏向感病亲本Lemont。在不同年份和遗传背景下检测到影响纹枯病相对病斑高度的主效QTL10个和互作QTL13个,其中2006年在TQ-IL群体定位到的6个主效QTL在2007年均得到验证,表明这些QTL具有较好年度间的重复性。QSh4是唯一在双向导入系背景下表达的QTL,该位点特青等位基因降低相对病斑高度,提高抗性水平。在TQ-ILs群体中定位到位于第10染色体RM216～RM311区间的QSb10a与在LT-IL群体中定位到的位于相邻区间RM222～RM216的QSb10b的基因作用方向不同,推断这两个QTL存在紧密连锁关系。绝大多数在TQ-IL群体中表达的主效及互作QTL在LT-ILs群体中不表达,表明水稻抗纹枯病QTL具有明显的遗传背景效应。通过比较作图,本研究定位到的其中8个QTL在以往不同群体中同样被检测到,这些主效QTL对通过分子标记辅助选择(marker-assisted selection,MAS)培育水稻抗纹枯病育种可能具有应用价值。指出标记辅助选择在不同遗传背景中能稳定表达的QTL或通过聚合不同抗病QTL是进一步提高水稻纹枯病抗性水平的一个有效途径。更多还原

【Abstract】 Genetic background and environmental effects of QTL for sheath blight resistance to the isolate RH-9(Rhizoctonia solani Kühn) were revealed using the reciprocal introgression line populations derived from the cross of Lemont/Teqing.Lemont is highly susceptible while Teqing resistant to RH-9.The relative lesion height(a ratio of lesion height to plant height,RLH) of TQ-ILs was normally distributed whereas that of LT-ILs was apparently inclined to the susceptible parent,Lemont.Total 10 main-effect QTLs and 13 epistatic QTLs affecting sheath blight resistance were mapped under different years and genetic back-grounds.Among them,six main-effect QTLs detected in 2006 were all verified in 2007,suggesting these QTLs had reliable per-formance across years.QSh4 was the only one QTL expressed under the reciprocal backgrounds and Teqing allele at this locus decreased RLH,suggesting the improvement of resistance level.QSh10a detected in the TQ-ILs and located in the region ofRM216–RM311 on the chromosome 10 and QSh10b detected in the LT-ILs in the neighboring region of RM222–RM216 were not the same gene but existed tight linkage as regards to different gene directions in different backgrounds.Most QTLs identified in TQ-ILs were not expressed in LT-ILs,indicating there was evident genetic background effect.By comparative mapping,8 QTLs detected in this study were located in the same or near regions that associated with sheath blight resistance identified in the previ-ous studies,suggesting these main-effect QTLs could be applied in rice breeding for sheath blight resistance by marker-assisted selection.As indicated in this study,it is an effective way to further improve sheath blight resistance by selecting the QTL stably expressed in different backgrounds or pyramiding different main-effect QTLs.更多还原