College of Horticulture, Northwest A&F University, Yangling, China; Key Laboratory of Protected Horticultural Engineering in Northwest, Ministry of Agriculture, Yangling, China; and State Key Laboratory of Crop Stress Biology for Arid Areas, Yangling, China.
College of Horticulture, Northwest A&F University, Yangling, China.
Plant Dis. 2018 Jul;102(7):1240-1245. doi: 10.1094/PDIS-04-17-0491-RE. Epub 2018 Apr 27.
Downy mildew (DM), caused by Pseudoperonospora cubensis, is one of the major foliar diseases prevailing in cucumber-growing areas. The mechanism of DM resistance in cucumber, particularly the plant introduction (PI) 197088 from India, is presently unclear. Quantitative trait locus (QTL) mapping is an efficient approach to studying DM resistance genes in cucumber. In this study, we performed QTL mapping for DM resistance in PI 197088 with 183 F-derived F (F) families from the cross between PI 197088 (DM resistant) and Changchunmici (DM susceptible). A linkage map was constructed using 141 simple sequence repeat markers. Phenotypic data were collected from seven independent experiments. In total, five QTL were detected on chromosomes 1, 3, 4, and 5 with DM resistance contributed by PI 197088. The QTL on chromosome 4, dm4.1, was reproducibly detected in all indoor experiments, which could explain 27% of the phenotypic variance detected. Additionally, dm1.1 and dm5.2 showed moderate effects, while dm3.1 and dm5.1 were minor-effect QTL. This study revealed the unique genetic architecture of DM resistance in PI 197088, which may provide important guidance for efficient use in cucumber breeding for DM resistance.
霜霉病（DM）由古巴假霜霉菌引起，是黄瓜种植区流行的主要叶部病害之一。黄瓜对 DM 的抗性机制，特别是来自印度的 PI 197088，目前尚不清楚。数量性状位点（QTL）作图是研究黄瓜 DM 抗性基因的有效方法。在这项研究中，我们利用 PI 197088（抗 DM）和长春密刺（感 DM）杂交产生的 183 个 F 衍生 F（F）家系，对 PI 197088 的 DM 抗性进行了 QTL 作图。使用 141 个简单重复序列标记构建了连锁图谱。从七个独立的实验中收集了表型数据。总共在染色体 1、3、4 和 5 上检测到 5 个 QTL，PI 197088 对 DM 抗性的贡献。染色体 4 上的 QTL dm4.1 在所有室内实验中均重复检测到，可解释检测到的表型方差的 27%。此外，dm1.1 和 dm5.2 表现出中等效应，而 dm3.1 和 dm5.1 是小效应 QTL。这项研究揭示了 PI 197088 对 DM 抗性的独特遗传结构，这可能为黄瓜抗 DM 育种的有效利用提供重要指导。
