Abstract：
CONCLUSIONS: Map-based cloning revealed that a mutation in a highly conserved amino acid of the CsGME gene encoding GDP-mannose 3,5-epimerase, causes the phenotype of little and wrinkled leaves in cucumbers. Leaf size is a critical determinant of plant architecture in cucumbers, yet only a few genes associated with this trait have been mapped or cloned. Here, we identified and characterized a mutant with little and wrinkled leaves, named lwl-1. Genetic analysis revealed that the phenotype of the lwl-1 was controlled by a single recessive gene. Through map-based cloning, the lwl-1 locus was narrowed down to a 12.22-kb region exclusively containing one fully annotated gene CsGME (CsaV3_2G004170). CsGME encodes GDP-mannose 3,5-epimerase, which is involved in the synthesis of ascorbic acid (ASA) and one of the components of pectin, RG-II. Whole-length sequencing of the 12.22 kb DNA fragment revealed the presence of only a non-synonymous mutation located in the sixth exon of CsGME in lwl-1, resulting in an amino acid alteration from Pro363 to Leu363. This mutation was unique among 118 inbred lines from cucumber natural populations. CsGME expression significantly reduced in various organs of lwl-1, accompanied by a significant decrease in ASA and pectin content in leaves. Both CsGME and Csgme proteins were localized to the cytoplasm. The mutant phenotype exhibited partial recovery after the application of exogenous boric acid. Silencing CsGME in cucumber through VIGS confirmed its role as the causal gene for lwl-1. Transcriptome profiling revealed that CsGME greatly affected the expression of genes related to the cell division process and cell plate formation. This study represents the first report to characterize and clone the CsGME in cucumber, indicating its crucial role in regulating leaf size and development.
摘要：
结论：基于图谱的克隆揭示了编码GDP-甘露糖3,5-差向异构酶的CsGME基因的高度保守氨基酸中的突变，导致黄瓜叶片很少和皱纹的表型。叶片大小是黄瓜植物结构的关键决定因素，然而，只有少数与该性状相关的基因被定位或克隆。这里,我们鉴定并鉴定了一个叶片很少且皱纹的突变体，名为lwl-1。遗传分析表明，lwl-1的表型受单个隐性基因控制。通过基于地图的克隆，lwl-1基因座缩小到仅包含一个完全注释基因CsGME（CsaV3_2G004170）的12.22kb区域。CsGME编码GDP-甘露糖3,5-差向异构酶，参与抗坏血酸（ASA）和果胶成分之一的合成，RG-II.12.22kbDNA片段的全长测序显示，仅存在位于lwl-1中CsGME第六外显子的非同义突变，导致从Pro363到Leu363的氨基酸改变。这种突变在黄瓜自然种群的118个自交系中是独特的。lwl-1各器官中CsGME表达显著降低,伴随着叶中ASA和果胶含量的显著降低。CsGME和Csgme蛋白均定位在细胞质中。应用外源硼酸后，突变表型表现出部分恢复。通过VIGS沉默黄瓜中的CsGME证实了其作为lwl-1的因果基因的作用。转录组分析显示，CsGME极大地影响了与细胞分裂过程和细胞板形成相关的基因的表达。这项研究代表了鉴定和克隆黄瓜中CsGME的第一份报告，表明其在调节叶片大小和发育中的关键作用。
