利用类番茄茄LA2951渐渗系群体鉴定番茄抗晚疫病QTL

【目的】利用来自番茄近缘野生种类番茄茄（Solanum lycopersicoides）LA2951的渐渗系群体，挖掘LA2951中潜在的抗晚疫病基因。【方法】采用离体叶片接种法，每片小叶背面接种10 μL菌液（2×104孢子囊/mL），在温度19℃和相对湿度70%-100%的条件下，第6天测量叶片病斑面积（lesion size，LS）和发病率（disease incidence，DI）。【结果】LA2951对晚疫病的抗性受QTL （quantitative trait loci）控制。接种番茄晚疫病T1,2小种，鉴定出Rpiq1b、Rpiq2b、Rpiq4b、Rpiq8a和Rpiq11等5个QTL，可显著减少叶片病斑面积；Rpiq1a、Rpiq2a和Rpiq8b等3个QTL，可明显降低叶片的发病率。接种致病力较强的小种T1,2,4，只鉴定出2个可减少DI的QTL（Rpiq4a和Rpiq5）。说明来自LA2951的QTL呈现明显的小种特异抗性。根据番茄高密度遗传图谱，本研究鉴定的QTL与前人鉴定出的番茄抗晚疫病QTL均同位。另外，无论是接种T1,2小种还是T1,2,4小种，均发现2个感病位点（Spiq4和Spiq10），它们分别位于第4条和第10条染色体短臂末端，可显著增加番茄叶片的DI。【结论】定位了来自类番茄茄LA2951的10个抗晚疫病QTL和2个感病QTL，抗病QTL呈现明显的小种特异抗性，研究结果为番茄抗晚疫病育种提供了理论参考。

Identification of QTLs Conferring Resistance to Late Blight in Solanum lycopersicoides LA2951 Introgression Line Population

【Objective】The objective of this study is to explore the potential loci for resistance to late blight of introgression line(IL) population derived from a nightshade related species Solanum lycopersicoides LA2951.【Method】 Detached-leaflet assay(DLA) was used for the artificial inoculation.The abaxial surface of each leaflet was inoculated with a drop of 10 μL sporangial suspension(2×104 sporangiums/mL),and the inoculated leaves were incubated at 19℃ with 70%-100% relative humidity.Lesion size(LS) of the leaf and disease incidence(DI) were measured 6 d after inoculation.【Result】The resistance of this wild species was controlled by quantitative trait loci(QTL).In total,5 QTLs(Rpiq1b,Rpiq2b,Rpiq4b,Rpiq8a,Rpiq11) were identified after inoculation with race T1,2,which significantly reduced LS,and 3 QTLs(Rpiq1a,Rpiq2a,Rpiq8b) were indentified which clearly reduced DI.However,only 2 QTLs(Rpiq4a and Rpiq5) reducing DI were indentified after inoculation with more virulent race T1,2,4.It proved that QTLs derived from LA2951 showed a clear race-specific resistance.Based on tomato high density genetic linkage map,all QTLs detected in this paper were co-localized with those previously identified in other tomato wild species.In addition,2 susceptibility QTLs(Spiq4 and Spiq10) increasing DI were identified after inoculation with both race T1,2 and race T1,2,4,which were located at the end of short arm of chromosome 4 and chromosome 10,respectively.【Conclusion】Ten resistance QTLs and 2 susceptibility QTLs were identified,and they presented a race-specific behavior.The results obtained in this paper provided a theoretical basis for breeding of late blight resistance in tomato.