Complete disruption of critical genes is generally accompanied by severe growth and developmental defects, which dramatically hinder its utilization in crop breeding. Identifying subtle changes, such as single-nucleotide polymorphisms (SNPs), in critical genes that specifically modulate a favorable trait is a prerequisite to fulfill breeding potential. Here, we found 2 SNPs in the E-class floral organ identity gene cucumber (Cucumis sativus) SEPALLATA2 (CsSEP2) that specifically regulate fruit length. Haplotype (HAP) 1 (8G2667A) and HAP2 (8G2667T) exist in natural populations, whereas HAP3 (8A2667T) is induced by ethyl methanesulfonate mutagenesis. Phenotypic characterization of 4 near-isogenic lines and a mutant line showed that HAP2 fruits are significantly longer than those of HAP1, and those of HAP3 are 37.8% longer than HAP2 fruit. The increasing fruit length in HAP1-3 was caused by a decreasing inhibitory effect on CRABS CLAW (CsCRC) transcription (a reported positive regulator of fruit length), resulting in enhanced cell expansion. Moreover, a 7638G/A-SNP in melon (Cucumis melo) CmSEP2 modulates fruit length in a natural melon population via the conserved SEP2-CRC module. Our findings provide a strategy for utilizing essential regulators with pleiotropic effects during crop breeding.

中文翻译：

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SEPALLATA 2 中的单核苷酸多态性是葫芦果实长度变化的基础


关键基因的完全破坏通常伴随着严重的生长和发育缺陷，这极大地阻碍了其在作物育种中的利用。识别特异性调节有利性状的关键基因中的细微变化，例如单核苷酸多态性 （SNP），是实现育种潜力的先决条件。在这里，我们在 E 类花器官同一基因黄瓜 （Cucumis sativus） SEPALLATA2 （CsSEP2） 中发现了 2 个 SNP，它们特异性地调节果实长度。单倍型 （HAP） 1 （8G2667A） 和 HAP2 （8G2667T） 存在于自然种群中，而 HAP3 （8A2667T） 是由甲磺酸乙酯诱变诱导的。4 个近等基因系和 1 个突变系的表型特征表明，HAP2 果实显著长于 HAP1，HAP3 果实比 HAP2 果实长 37.8%。HAP1-3 中果长的增加是由于对 CRABS CLAW （CsCRC） 转录 （据报道的果长的正调节因子） 的抑制作用降低引起的，导致细胞扩增增强。此外，甜瓜 （Cucumis melo） CmSEP2 中的 7638G/A-SNP 通过保守的 SEP2-CRC 模块调节天然甜瓜种群的果实长度。我们的研究结果为在作物育种过程中利用具有多效性作用的基本调节因子提供了一种策略。