甜瓜果形基因CmSUN25-26-27a的鉴定和分子标记

Identification of melon fruit shape gene CmSUN25-26-27a and molecular marker development

【目的】挖掘甜瓜果形相关基因,为甜瓜果实形状的遗传改良提供理论基础。【方法】通过全基因组鉴定,系统发育分析,结合表达量与果形的关联分析来鉴定参与甜瓜果形调控的CmSUN基因,并利用候选基因在自然群体中的序列变异开发相关分子标记。【结果】通过全基因组鉴定及系统发育分析,鉴定到甜瓜CmSUN家族的CmSUN25-26-27a基因。该基因在开花当天的雌花中有显著的表达,并且在不同果形甜瓜中的表达量与果形指数(fruit shape index,FSI)呈正相关关系;对200份自然群体的序列分析发现,CmSUN25-26-27a基因编码区存在一个SNP-Single Nucleotide Polymorphism(A/G),导致了编码氨基酸的非同义突变,含有CmSUN25-26-27a^(A)等位基因的厚皮甜瓜的FSI显著高于含CmSUN25-26-27a^(G)等位基因的厚皮种质。该SNP位点将厚皮甜瓜按果形大致分为FSI>1.5(A)和FSI<1.5(G)两种类型。根据该SNP位点设计了用于区分甜瓜果形的dCAPS标记。【结论】CmSUN25-26-27a同源基因广泛参与葫芦科作物的果形调控,该基因在甜瓜中的表达量及序列变异与甜瓜FSI具有显著相关性。

【Objective】The purpose of this study is to explore the genes related to the shape of melon fruits in order to provide a theoretical basis for genetic improvement in melon fruit breeding.【Method】This study identified the CmSUN gene involved in melon fruit shape regulation through whole genome identification,phylogenetic analysis,and association analysis between expression levels and fruit shape.The sequence variation of this gene in natural populations is utilized to develop relevant molecular markers.【Result】Through whole-genome identification and phylogenetic analysis,the CmSUN25-26-27a gene in the melon CmSUN family was identified.This gene shows significant expression in female flowers on the day of flowering and its expression level in different fruit-shaped melons is positively correlated with the fruit shape index(FSI).Through sequence analysis of 200 natural populations.It was found that a SNP-Single Nucleotide Polymorphism(A/G)in the coding region of CmSUN25-26-27a gene,resulting in a non-synonymous mutation in the encoded amino acid.Melons with CmSUN25-26-27a^(A) gene have significantly higher FSI than those with CmSUN25-26-27a^(G) gene.This SNP site roughly divides thick-skinned melons into two types based on fruit shape:FSI>1.5(A)and FSI<1.5(G),and the dCAPS markers for distinguishing sweet melon shape are designed according to this SNP site.【Conclusion】CmSUN25-26-27a homologous genes play a significant role in regulating fruit shape in cucurbit crops.The expression level and sequence variations of this gene in melons are closely correlated with melon fruit shape index(FSI).