Powdery mildew (PM), a common disease of many major crop species, including melon (Cucumis melo L.), affects plant growth and fruit quality and seriously reduces production. Using a combined morphological and molecular approach, we attribute the PM pathogen that naturally occurs in melon to Podosphaera xanthii, and specifically to physiological race 1. An investigation into the genetic basis of PM resistance in melon using the resistant accession ‘PI 164637’ and susceptible counterpart ‘HDZ’ reveals dominant inheritance of PM resistance at the seedling stage, supported by F2 and backcross population segregation ratios. Adult plant assessments indicate a major gene with an additive effect for PM resistance. Bulk segregant analysis coupled with high-throughput sequencing identified a significant quantitative trait locus on chromosome 6 that is associated with PM resistance. Genetic mapping narrowed down the candidate region to 63.5 kb using InDel molecular markers, harboring 12 candidate genes. The marker chr06_indel_5 047 127 demonstrated high accuracy in screening PM resistance in an F2 segregating population and 30 inbred lines as natural populations. Functional annotation and expression analysis of candidate genes revealed that MYB transcription factor MELO3C006700, GATA transcription factor MELO3C028829 and heparanase-like protein MELO3C006697 are promising candidate genes for PM resistance in melon. The genetic architecture underlying this resistance in melon offers valuable insights for breeding programs, and the identified markers, especially chr06_indel_5 047 127, may enable practical applications for marker-assisted selection in developing PM-resistant melon varieties.

中文翻译：

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对甜瓜 （Cucumis melo L.） 中与白粉病抗性相关的候选基因进行精细定位和鉴定


白粉病 （PM） 是包括甜瓜 （Cucumis melo L.） 在内的许多主要作物物种的常见病害，影响植物生长和果实品质，严重降低产量。使用形态学和分子学相结合的方法，我们将甜瓜中天然存在的 PM 病原体归因于 Podosphaera xanthii，特别是生理种族 1。使用抗性种质 'PI 164637' 和易感对应物 'HDZ' 对甜瓜 PM 抗性的遗传基础的调查揭示了 PM 抗性在幼苗阶段的显性遗传，并得到 F2 和回交种群分离比率的支持。成虫评估表明一个对 PM 抗性具有加性效应的主要基因。批量分离分析与高通量测序相结合，确定了 6 号染色体上与 PM 耐药性相关的重要数量性状位点。遗传定位使用 InDel 分子标记将候选区域缩小到 63.5 kb，其中包含 12 个候选基因。标记chr06_indel_5 047 127 在 F2 分离种群和 30 个自然种群的自交系中筛选 PM 抗性方面表现出很高的准确性。候选基因的功能注释和表达分析显示，MYB 转录因子 MELO3C006700 、 GATA 转录因子 MELO3C028829 和乙酰肝素酶样蛋白 MELO3C006697 是甜瓜 PM 耐药的有前途的候选基因。甜瓜这种抗性背后的遗传结构为育种计划提供了有价值的见解，鉴定出的标记，尤其是 chr06_indel_5 047 127，可能为标记辅助选择在开发抗 PM 的甜瓜品种中提供了实际应用。