Department of Plant and Environmental Sciences, Coastal Research and Education Center, Clemson University, Charleston, SC, 29414, USA.
US Vegetable Laboratory, USDA, ARS, 2700 Savannah Highway, Charleston, SC, 29414, USA.
Theor Appl Genet. 2021 Aug;134(8):2577-2586. doi: 10.1007/s00122-021-03843-w. Epub 2021 May 5.
This is the first identification of QTLs underlying resistance to Pseudoperonospora cubensis in Cucumis melo using a genetically characterized isolate. Pseudoperonospora cubensis, causal organism of cucurbit downy mildew (CDM), is one of the largest threats to cucurbit production in the eastern USA. Currently, no Cucumis melo (melon) cultivars have significant levels of resistance. Additionally, little is understood about the genetic basis of resistance in C. melo. Recombinant inbred lines (RILs; N = 169) generated from a cross between the resistant melon breeding line MR-1 and susceptible cultivar Ananas Yok'neam were phenotyped for CDM resistance in both greenhouse and growth chamber studies. A high-density genetic linkage map with 5,663 binned SNPs created from the RIL population was utilized for QTL mapping. Nine QTLs, including two major QTLs, were associated with CDM resistance. Of the major QTLs, qPcub-10.1 was stable across growth chamber and greenhouse tests, whereas qPcub-8.2 was detected only in growth chamber tests. qPcub-10.1 co-located with an MLO-like protein coding gene, which has been shown to confer resistance to powdery mildew and Phytophthora in other plants. This is the first screening of C. melo germplasm with a genetically characterized P. cubensis isolate.
这是首次利用遗传特征明确的分离物鉴定出黄瓜对古巴假霜霉病（ Pseudoperonospora cubensis ）抗性的 QTL。古巴假霜霉病是瓜类霜霉病（ cucurbit downy mildew ，CDM）的致病因子，是美国东部最大的瓜类生产威胁之一。目前，没有黄瓜（甜瓜）品种具有显著水平的抗性。此外，对黄瓜中抗性的遗传基础知之甚少。利用从抗霜霉病的甜瓜育种系 MR-1 和易感品种 Ananas Yok'neam 杂交产生的重组自交系（ RIL ； N = 169），在温室和生长室研究中对黄瓜霜霉病抗性进行了表型分析。利用来自 RIL 群体的 5663 个分箱 SNP 创建了高密度遗传连锁图谱，用于 QTL 作图。与黄瓜霜霉病抗性相关的 9 个 QTL，包括 2 个主效 QTL。其中，qPcub-10.1 在生长室和温室试验中均稳定，而 qPcub-8.2 仅在生长室试验中检测到。qPcub-10.1 与一个 MLO 样蛋白编码基因共定位，该基因已被证明在其他植物中对白粉病和 Phytophthora 具有抗性。这是首次用遗传特征明确的古巴假霜霉菌分离物筛选黄瓜种质资源。
