黄瓜黄叶突变基因yl-5的鉴定与分析

Identification and Analysis of Yellow Leaf Mutant Gene yl-5 in Cucumber(Cucumis sativus L.)

叶色突变体是研究叶绿素代谢途径、叶绿体发育过程和植物光合作用的生理特性及分子机制的理想材料。本研究从黄瓜Tnt1转座子插入突变体库中获得黄叶突变体yl-5,将其与野生型黄瓜自交系S06杂交,构建F_(2)分离群体,遗传分析表明该黄叶表型为隐性单基因控制。通过图位克隆手段,对yl-5进行定位与克隆,发现其定位于3号染色体22.47~22.55 Mb物理区间内,其间包含12个基因。通过基因组重测序分析,发现只有Csa3G588450在两亲本间存在序列差异,其突变形式为基因内部插入Tnt1转座子,导致基因结构被破坏。该基因内标记与黄叶表型完全共分离,说明Csa3G588450是yl-5的候选基因。生物信息学分析显示,Csa3G588450预测编码叶绿体30S核糖体蛋白S21,在拟南芥中的同源基因为LPE2,其突变导致拟南芥光合效率降低,与yl-5突变体表型相似。该基因的克隆为黄瓜叶绿体发育的分子机制研究打下基础。

Leaf color mutants are ideal materials for studying chlorophyll metabolism pathway,chloroplast development,physiological characteristics and molecular mechanism of plant photosynthesis.In this study,yellow leaf mutant yl-5 was obtained from Tnt1 transposon insertion mutant library of cucumber(Cucumis sativus L.)and crossed with wild type cucumber inbred line S06 to construct F2segregation population.Genetic analysis showed that the yellow leaf phenotype was controlled by recessive single gene.By map-based cloning,yl-5 was located in the22.47~22.55 Mb region of chromosome 3,which contained 12 genes.Through genome re-sequencing analysis,it was found that only Csa3G588450 had sequence difference between the two parents.The mutation form of Csa3G-588450 was the insertion of Tnt1 transposon into the gene,resulting in the destruction of gene structure.The internal marker of the gene was completely co-segregated with the yellow leaf phenotype,indicating that Csa3G588450 is a candidate gene of yl-5.Bioinformatics analysis showed Csa3G588450 predicted to encode chloroplast 30S ribosomal protein S21,and the homologous gene in Arabidopsis was LPE2.The mutation resulted in the decrease of photosynthetic efficiency in Arabidopsis,which was similar to the phenotype of yl-5 mutant.The cloning of this gene laid a foundation for the molecular mechanism of cucumber chloroplast development.