菠菜抗霜霉病基因精细定位

Spinach is one of the important vegetable crops in China. Downy mildew, caused by pathogen, is one of the most destructive diseases on spinach. However, there are few reports on the spinach downy mildew resistance. Up to now, only one SCAR marker is reported to be linked to the resistance gene (pfs-1). In our research group, the races 8 of Downy mildew (pfs8) collected from many provinces have been identified using the gene-for-gene model based on the reaction with the host differentials. Additionally, the germplasm with resistance to the related races is screened and identified. Using the cross of resistant germplasm SP122 and susceptible material SP-121, the F2 population has been constructed for mapping the resistance gene in SP122. The results of the phenotyping F2 population inoculated with pfs8 indicated that Downy mildew resistance gene in SP122 was a single dominant gene. Based on the previous studies and reference genome sequence information, we intend to resequence the germplasm SP122 and SP-121, develop the SSR, Indel and SNP markers and map the resistance gene. Fine mapping the resistance gene will be done via further expanding F2 population and developing molecular markers in the preliminarily mapped region. According to the disease resistance mechanism, the candidate gene with NBS-LRR structure will be identified and analyzed by developing the co-segregation markers and qRT-PCR test. This work will lay a foundation for further revealing the resistance mechanism and breeding the spinach varieties resistant to downy mildew.

菠菜是我国重要的蔬菜作物之一，霜霉病是菠菜生产中最主要的病害，对菠菜的生产造成极大危害。但是国内外鲜少有菠菜抗霜霉病基因研究，仅报道了一个与抗病基因连锁的SCAR标记。项目组对我国菠菜霜霉生理小种进行鉴定，其中生理小种8（pfs8）发病广，危害严重；项目组筛选出抗病资源，以抗pfs8亲本SP-122和感pfs8亲本SP-121构建F2群体，其霜霉病抗性受一个显性基因控制。借助菠菜参考基因组信息，项目组拟对亲本SP-122和SP-121进行重测序，开发大量的SSR、Indel和SNP标记。采用BSA法，进行抗病基因连锁标记筛选，对抗病基因初定位；并进一步开发分子标记，扩大F2群体，对抗病基因精细定位。根据植物抗病机制，筛选具有NBS-LRR结构的R基因为候选基因，开发基因标记进行共分离验证及RT-PCR验证，进一步确定候选基因。此项工作将为揭示菠菜霜霉病抗性机制和培育抗霜霉病品种奠定基础。

菠菜是我国重要的蔬菜作物之一，霜霉病是菠菜生产中最主要的病害，对菠菜的生产造成极大危害。项目组首次对我国菠菜霜霉病生理小种鉴定分析，结果表明我国不同地区存在不同的霜霉病生理小种，其中北京地区主要是9号生理小种，山西地区主要是5号生理小种，山东地区主要是8号生理小种。项目组采用SLAF-seq法构建了菠菜全基因组高密度遗传图谱，共构建6个连锁群，上图4,080个SNP标记，总图距为1,125.97cM，依据遗传图谱SNP开发了300个KASP标记。项目组在以上基础上，筛选抗5号、9号生理小种的抗病资源，以抗病亲本12S3和感病亲本12S4构建F2群体，其霜霉病抗性受一个显性基因RPF1控制，通过BSA筛选到21个与抗病基因连锁的分子标记，将抗病基因定位在1号连锁群上0.9Mb的区间内；筛选抗8号生理小种的抗病资源，以抗病亲本SP-122和感病亲本SP-121构建F2群体，其霜霉病抗性受一个显性基因RPF2控制，通过BSA法筛选到2个与抗病基因连锁的分子标记。以上抗病基因的定位工作仍在进行中，为下一步抗病基因的克隆及功能分析奠定基础。