Commercial value of cucumber is primarily driven by fruit quality. However, breeding goals frequently focus on production constraints caused by biotic and abiotic stresses. As sources of resistances are often present in unadapted germplasm, we sought to provide morphological and genetic information characterizing the diversity of fruit quality traits present in the CucCAP cucumber core collection. These 388 accessions representing >96% of the genetic diversity for cucumber present in the U.S. National Plant Germplasm System harbor important sources of resistances and extensive morphological diversity. Data were collected for skin color, length/diameter ratio (L/D), tapering, curvature, and spine density for young fruits [5-7 days post-pollination (dpp)], and length, diameter, L/D, skin color, netting, seed cavity size, flesh thickness, hollowness, and flesh color for mature fruits (30-40 dpp. Significant associations of SNPs with each trait were identified from genome-wide association studies (GWAS). In several cases, QTL for highly correlated traits were closely clustered. Principal component analysis, driven primarily by the highly correlated traits of fruit length, young and mature L/D ratios, and curvature showed a clear divergence of East Asian accessions. Significant SNPs contributing to the longest fruits, including development-stage specific QTL, were distributed across multiple chromosomes, indicating broad genomic effects of selection. Many of the SNPs identified for the various morphological traits were in close vicinity to previously identified fruit trait QTL and candidate genes, while several novel genes potentially important for these traits were also identified.

中文翻译：

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挖掘黄瓜核心收藏品：水果品质特征形态多样性的表型和遗传特征


黄瓜的商业价值主要由水果质量驱动。然而，育种目标通常集中在由生物和非生物胁迫引起的生产限制上。由于抗性来源通常存在于未适应的种质中，我们试图提供形态学和遗传信息，以表征 CucCAP 黄瓜核心收藏中存在的果实品质性状的多样性。这 388 种质代表了美国国家植物种质系统中黄瓜遗传多样性的 >96%，具有重要的抗性来源和广泛的形态多样性。收集幼果的表皮颜色、长度/直径比 （L/D）、锥形、曲率和脊柱密度 [授粉后 5-7 天 （dpp）] 以及成熟果实的长度、直径、L/D、皮肤颜色、网、种子腔大小、果肉厚度、空心度和果色 （30-40 dpp.从全基因组关联研究 （GWAS） 中确定了 SNP 与每个性状的显着关联。在一些情况下，高度相关性状的 QTL 紧密聚集。主要由果实长度、年轻和成熟 L/D 比以及曲率高度相关的性状驱动的主成分分析表明，东亚种质之间存在明显差异。导致最长果实的重要 SNP（包括发育阶段特异性 QTL）分布在多个染色体上，表明选择具有广泛的基因组效应。为各种形态性状鉴定的许多 SNP 与先前鉴定的水果性状 QTL 和候选基因非常接近，同时还鉴定了几个对这些性状可能重要的新基因。