甜瓜PI390452霜霉病抗性基因的QTL定位

QTL Mapping of Resistance Genes to Downy Mildew in Cucumis melo ssp. melo PI390452

【目的】研究甜瓜抗霜霉病资源PI390452,分析PI390452抗性遗传规律,并对抗病基因进行QTL定位分析,为甜瓜抗霜霉病分子辅助育种奠定基础。【方法】用甜瓜霜霉病病原菌[Pseudoperonospora cubensis(Berk.et Curt.)Rostov.]对PI390452×卡拉克赛(高感霜霉病)杂交后代F2分离群体及F2∶3家系人工接种鉴定,以F2分离群体为研究对象,基于ICu GI已构建对应分子标记连锁图谱,应用BSA法和1 090对甜瓜SSR引物进行连锁遗传分析,采用QTL Ici Mapping软件定位霜霉病QTL位点。【结果】资源PI390452霜霉病抗性符合数量性状遗传的特点。共检测到3个霜霉病抗性基因的QTL位点qR1-1-1、qR1-3-1、qR2-2-1,分别位于chr-5、chr-10、chr-9上,qR2-2-1表型变异率最大为80.84%。【结论】位于chr-9上的qR2-2-1是控制甜瓜霜霉病主效QTL位点,为甜瓜抗霜霉病分子标记辅助育种、抗病基因精细定位、克隆提供了技术支持。

[ Objective] The Cucumis melo ssp. melo PI390452 with high resistance to downy mildew was used as materials for the study of the genetic law of resistance to pi390452 resistance. And the resistance gene went through QTL mapping to lay the foundation and provide a theoretical basis for the resistance mechanism and molecular assistant selection （MAS） breeding. [ Method] An artificial inoculation method was adopted to test the degree of resistance to Pseudoperonospora cubensis （ Berk. etCurt. ） for the F2：3 family lines derived from the cross of PI390452 x ＂kalakesai ＂ （susceptible Farmholding variety）. SSR analysis, combined with bulked segregation analysis （BSA）, was done on the DNA of F2 population using 1,090 pairs of SSR primers. QTL IciMapping software were used to construct SSR linkages and to make sure the corresponding relations between these SSR linkages and ICuGI was constructed corresponding molecular marker linkage map. QTL analysis on downy mildew resistance genes was conducted by QTL IciMapping software. [ Result] The inheritance of the re- sistance gene to downy mildew in PI390452 fit to the inheritance law of quantitative trait. Three QTLs named qR1 - 1 - 1, qR1 - 3 - 1 and qR2 - 2 - I for the resistance gene to downy mildew were detected in this study. qR1 -1 -1 ,qR1 -3 -1 and qR2 -2 -1 were located on Chr. 5, Chr. 9and Chr. 10. The QTL of qR2 -2 -1 accounted for the highest phenotypic variation of 80.84%. [ Conclusion] The QTL of qR2 -2 - 1 located on Chr. 9 was the major QTL. The results in this study will be of great benefit to fine mapping and gene cloning for the major QTL of downy mildew resistance gene, also the results will lay a good foundation for melon MAS resistance breeding .