黄瓜白粉病抗性基因定位及候选基因分析

【目的】通过对黄瓜白粉病抗性基因的精细定位,明确抗性基因的候选区段,为进一步克隆基因及解析基因功能奠定基础。【方法】本研究选用高抗白粉病资源(自交系‘74’)和感白粉病资源(自交系‘80’)配制杂交组合,构建F_1、F_2群体,利用单囊壳白粉菌鉴定亲本及群体白粉病抗性并进行遗传分析;采用BSA-seq的方法对黄瓜白粉病抗性基因进行初步定位,在此基础上在候选区段开发分子标记,进一步精细定位白粉病抗性基因。【结果】分离群体单株表型鉴定结果表明,自交系74的抗性是由不完全隐性基因控制的。BSA-seq技术初步将抗性基因定位于5号染色体15—25 Mb位置,命名为PM 74。最终,利用分子标记将抗性基因定位于SSR15321和SSR07531之间,遗传距离为3.06 c M,物理距离为238 444 bp,可解释41.95%的表型变异。生物信息学分析表明在候选区段内包含有17个候选基因,其中Cucsa.275630为TIR-NBS-LRR类基因。【结论】本研究将黄瓜白粉病抗性基因精细定位到约238 kb的候选区段内,区段内包含有一个TIR-NBS-LRR基因,该基因将是今后研究的重点候选基因。

Fine Mapping and Analysis Candidate Gene to Powdery Mildew in Cucumber (Cucumis sativus L.)

【Objective】Identification and fine mapping of the candidate region and the gene associated with powdery mildew resistance is significant for gene cloning and functional genomics research in cucumber breeding. 【Method】Powdery mildew resistant cucumber line was identified using single capsule inoculation. Bulked segregant analysis sequencing (BSA-seq) technology was intended to complete the primary mapping of the PMR gene. 【Result】 Resistance identification showed inbred lines 74 exhibited excellent resistance to powdery mildew, in contrast, the inbred lines 80 showed high susceptibility. These two genotypes were used to construct F₁ segregation population which was then extended to F₂ population for an inheritance study. Our results indicated the resistance gene from inbred line 74 was partial-recessive inherited. BSA-seq localized the major resistance gene, named PM⁷⁴, to a 15-25 Mb genomic region in cucumber on chromosome 5. The resistance gene was further located with a 23 844 bp physical distance between SSR15321 and SSR07531 at the genetic distance of 3.06 cM and could explain 41.95% phenotypic variation. 17 annotated genes were found within the predicted candidate region, including one gene belongs to TIR-NBS-LRR gene family, named Cucsa.275630. 【Conclusion】This study mapped a PMR gene within the 238 kb physical interval on Chromosome 5, a TIR-NBS-LRR type gene was identified and would be focused in the future study.