Shi Jiale, Yang Congji, Qin Yuanyuan, Liu Qingqing, Hua Shengqi, Wu Defeng, Dong Wei
State Key Laboratory of Cotton Biology, School of Life Sciences, Henan University, Kaifeng, 475001, China.
School of Life Science, Henan University, Kaifeng, Henan, 475004, People's Republic of China.
BMC Plant Biol. 2025 Jan 23;25(1):92. doi: 10.1186/s12870-025-06071-2.
In watermelon (Citrullus lanatus), lesion mimic is a rare, valuable trait that can be used by breeders for selection at early growth stages. In this study, we tested a seven-generation family to determine the inheritance and genetic basis of this trait. As revealed by analysis of the lesion mimic mutant clalm, this trait is controlled by a single dominant gene. Whole genome resequencing-bulked segregant analysis demonstrated that this gene is located on chromosome 4 from 3,760,000 bp to 7,440,000 bp, a region corresponding to a physical distance of 3.68 Mb encompassing approximately 72 annotated genes. There are 6 genes with non-synonymous mutation SNP sites. The predicted target gene, ClCG04G001930, encodes a Phytoalexin deficient 4 (PAD4), a protein that plays an important regulatory role in leaf senescence in many plant species. According to quantitative real-time PCR analysis, the expression level of ClCG04G001930 was significantly higher in the clalm mutant than in normal watermelon. Twenty-five SNPs were identified in the ClCG04G001930 gene of F individuals of the clalm mutant. Overexpression the ClCG04G001930 gene, designated as ClPAD4, yielded transgenic lines whose leaves gradually developed chlorotic lesions over 3 weeks. RNA interference of the ClPAD4 yielded transgenic lines whose cotyledon prone to diseased over 2 weeks. Our results suggest that ClPAD4 might be the candidate gene responsible for lesion mimic in the clalm mutant. Our findings may serve as a foundation for elucidating the mechanism underlying the molecular metabolism of programmed cell death and should be useful for marker-assisted selection breeding in watermelon.
在西瓜（Citrullus lanatus）中，类病变是一种罕见且有价值的性状，育种者可在早期生长阶段利用该性状进行选择。在本研究中，我们对一个七代家系进行了测试，以确定该性状的遗传方式和遗传基础。通过对类病变突变体clalm的分析表明，该性状由单个显性基因控制。全基因组重测序-混合分组分析法表明，该基因位于4号染色体上3,760,000 bp至7,440,000 bp的区域，该区域对应3.68 Mb的物理距离，包含约72个注释基因。有6个基因具有非同义突变SNP位点。预测的目标基因ClCG04G001930编码一种植物抗毒素缺陷4（PAD4），该蛋白在许多植物物种的叶片衰老中起重要调控作用。根据定量实时PCR分析，ClCG04G001930在clalm突变体中的表达水平显著高于正常西瓜。在clalm突变体F个体的ClCG04G001930基因中鉴定出25个SNP。过表达ClCG04G001930基因（命名为ClPAD4）产生的转基因株系在3周内叶片逐渐出现褪绿病变。对ClPAD4进行RNA干扰产生的转基因株系子叶在2周内易发病。我们的结果表明，ClPAD4可能是clalm突变体中类病变的候选基因。我们的发现可为阐明程序性细胞死亡分子代谢的潜在机制奠定基础，并且对西瓜的分子标记辅助选择育种具有重要意义。
