Key Laboratory of Biology and Genetic Improvement of Horticulture Crops (Northeast Region), Ministry of Agriculture and Rural Affairs, College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin, Heilongjiang Province, China.
College of Horticulture and Landscape Architecture, Northeast Agricultural University, Harbin, 150030, Heilongjiang Province, China.
Theor Appl Genet. 2022 Jun;135(6):1909-1921. doi: 10.1007/s00122-022-04083-2. Epub 2022 Mar 31.
Genetic analysis revealed that CmCLV3 is a candidate gene for the variation in melon carpel number. Carpel number (CN) is an important trait in melon. Three-CN melon fruit is oval, while 5-CN melon fruit has a round or flat shape. Herein, a genetic analysis of a population in which the CN locus was segregated indicated that 3-CN is controlled by a major dominant effective gene. Bulked segregant analysis and initial linkage mapping placed the CN locus in a 6.67 Mb region on chromosome 12, and it was narrowed to 882.19 kb with molecular markers and recombinant plants. Fine mapping with a large F population containing 1026 individuals further narrowed the locus to an 83.98 kb region harboring five annotated genes. Gene structure alignment between the parental lines revealed MELO3C035640.2 (annotated as CLAVATA3, CmCLV3) as the best candidate gene for the CN trait. CmCLV3 was more highly expressed in 3- than 5-CN lines and specifically expressed in terminal buds rather than in young leaves, hypocotyls, and roots. The CmCLV3 coding region was cloned from eight 3- or 5-CN melon accessions, and a nonsynonymous SNP site was highly correlated with CN variation. This SNP site was also related to CN variations among 40 melon lines according to their resequencing data, causing a helix alteration in the CmCLV3 protein. Promoter region sequence alignment and activity analysis showed that, unlike in cucumber and tomato, CmCLV3 promoter variation and activity were not the main reasons for CN alteration. Overall, this study provides a genetic resource for melon fruit development research and molecular breeding tools for melon CN improvement.
遗传分析表明，CmCLV3 是甜瓜心皮数量变异的候选基因。心皮数量（CN）是甜瓜的一个重要性状。三心皮甜瓜果实为椭圆形，五心皮甜瓜果实为圆形或扁平形。在此，对 CN 基因座分离的群体进行遗传分析表明，三心皮受一个主要显性有效基因控制。混池分离分析和初步连锁图谱将 CN 基因座定位在第 12 号染色体上的 6.67 Mb 区域，利用分子标记和重组植株将其缩小到 882.19 kb。利用包含 1026 个个体的大 F 群体进行精细作图，进一步将基因座缩小到一个包含五个注释基因的 83.98 kb 区域。亲本系之间的基因结构比对显示 MELO3C035640.2（注释为 CLAVATA3，CmCLV3）是 CN 性状的最佳候选基因。CmCLV3 在三心皮线中比五心皮线表达更高，并且在顶端芽中特异性表达，而不在幼叶、下胚轴和根中表达。从八个三心皮或五心皮甜瓜品系中克隆了 CmCLV3 编码区，一个非同义 SNP 位点与 CN 变异高度相关。根据重测序数据，该 SNP 位点也与 40 个甜瓜品系的 CN 变异有关，导致 CmCLV3 蛋白中的螺旋改变。启动子区域序列比对和活性分析表明，与黄瓜和番茄不同，CmCLV3 启动子变异和活性不是 CN 改变的主要原因。总的来说，这项研究为甜瓜果实发育研究提供了遗传资源，为甜瓜 CN 改良提供了分子育种工具。
