Fourteen cucumber lines were tested for genetic homozygosity and performed pairwise comparison to identify a pair with the highest DNA polymorphic level. Cucumber accessions CSL0067 and CSL0139 were selected to generate 315 F 2 populations. The genetic linkage map based on 66 polymorphic SSR markers was constructed. It composed of eight linkage groups (LGs) spanning 474.4 cM. Downy mildew disease reaction was evaluated in cotyledons, first and second true leaf on 7, 10, and 14 day after inoculation. The results showed that downy mildew resistance was controlled by multiple recessive genes. The susceptible to resistant ratio of F 2 progenies fit 9:7 susceptible/resistant segregation types corresponding to duplicate recessive epistasis. Fourteen QTLs were detected. The phenotypic variance ranged from 5.0 to 12.5%, while LOD values ranged from 3.538 to 9.165. Two major QTLs and two QTL hotspots were identified. Moreover, the additive effects data explained that these QTL reduced downy mildew susceptibility.

中文翻译：

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基于SSR标记的遗传连锁图谱鉴定黄瓜霜霉病抗性QTL

测试了 14 个黄瓜品系的遗传纯合性，并进行了成对比较以鉴定具有最高 DNA 多态性水平的一对。选择黄瓜种质CSL0067 和CSL0139 以产生315 个F 2 种群。构建了基于66个多态SSR标记的遗传连锁图谱。它由跨越 474.4 cM 的八个连锁群 (LGs) 组成。在接种后第 7、10 和 14 天评估子叶、第一和第二真叶中的霜霉病反应。结果表明，霜霉病抗性受多个隐性基因控制。F 2 后代的易感抗性比符合9:7易感/抗性分离类型，对应于重复隐性上位。检测到 14 个 QTL。表型变异范围为 5.0% 至 12.5%，而 LOD 值范围为 3。538 到 9.165。确定了两个主要的 QTL 和两个 QTL 热点。此外，加性效应数据解释了这些 QTL 降低了霜霉病的易感性。