Powdery mildew is a disease with one of the most substantial impacts on cucumber production globally. The most efficient approach for controlling powdery mildew is the development of genetic resistance; however, few genes associated with inherent variations in cucumber powdery mildew resistance have been identified as of yet. In this study, we re-sequence 299 cucumber accessions, which are divided into four geographical groups. A genome-wide association study identifies 50 sites significantly associated with natural variations in powdery mildew resistance. Linkage disequilibrium analysis further divides these 50 sites into 32 linkage disequilibrium blocks containing 41 putative genes. Virus-induced gene silencing and gene expression analysis implicate CsGy5G015960, which encodes a phosphate transporter, as the candidate gene regulating powdery mildew resistance. On the basis of the resequencing data, we generate five CsGy5G015960 haplotypes, identifying Hap.1 as the haplotype most likely associated with powdery mildew resistance. In addition, we determine that a 29-bp InDel in the 3′ untranslated region of CsGy5G015960 is responsible for mRNA stability. Overexpression of CsGy5G015960Hap.1 in the susceptible line enhances powdery mildew resistance and phosphorus accumulation. Further comparative RNA-seq analysis demonstrates that CsGy5G015960Hap.1 may regulate cucumber powdery mildew resistance by maintaining a higher H2O2 level through the depletion of multiple class III peroxidases. Here we identify a candidate powdery mildew-resistant gene in cucumber using GWAS. The identified gene may be a promising target for molecular breeding and genetic engineering in cucumber to enhance powdery mildew resistance.

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全基因组关联研究揭示了黄瓜白粉病抗性的分子机制


白粉病是一种对全球黄瓜生产影响最严重的病害之一。控制白粉病最有效的方法是发展遗传抗性；然而，迄今为止，与黄瓜白粉病抗性固有变异相关的基因还很少被识别。在这项研究中，我们对 299 个黄瓜种质进行了重新测序，将其分为四个地理组。一项全基因组关联研究确定了 50 个与白粉病抗性自然变异显着相关的位点。连锁不平衡分析进一步将这 50 个位点分为 32 个连锁不平衡块，包含 41 个推定基因。病毒诱导的基因沉默和基因表达分析表明，编码磷酸盐转运蛋白的 CsGy5G015960 是调节白粉病抗性的候选基因。根据重测序数据，我们生成了五个 CsGy5G015960 单倍型，将 Hap.1 识别为最有可能与白粉病抗性相关的单倍型。此外，我们确定 CsGy5G015960 3' 非翻译区中的 29 bp InDel 负责 mRNA 稳定性。 CsGy5G015960Hap.1 在易感品系中的过度表达增强了白粉病抗性和磷积累。进一步的比较 RNA-seq 分析表明，CsGy5G015960Hap.1 可以通过消耗多种 III 类过氧化物酶来维持较高的 H2O2 水平，从而调节黄瓜白粉病抗性。在这里，我们使用 GWAS 鉴定了黄瓜中的候选白粉病抗性基因。所鉴定的基因可能是黄瓜分子育种和基因工程的一个有前景的靶标，以增强白粉病的抗性。