NS encodes an auxin transporter that regulates the ‘numerous spines’ trait in cucumber (Cucumis sativus) fruit

第一作者：Xiaoping Liu

第一单位：农科院蔬菜花卉研究所

第一通讯：Shengping Zhang

 Abstarct 

背景回顾：Fruit spine is an important agronomic trait in cucumber and the “numerous spines” cucumber varieties are popular in Europe and West Asia. 

果刺是黄瓜的一种重要农艺性状，密刺黄瓜品种在欧洲和西亚市场很受欢迎。

提出问题：Although the classical genetic locus of numerous spines (ns) was reported more than two decades ago, the NS gene has not been cloned yet. 

尽管ns（numerous spines）遗传位点在两个世纪之前就已经被报道，但是NS基因还没有被克隆。

结果1-GWAS鉴定NS：In this study, nine genetic loci for the different densities of fruit spines were identified by a genome-wide association study (GWAS). Among the nine loci, fsdG2.1 was closely associated with the classical genetic locus ns, in which harbors a candidate gene Csa2G264590. 

本文中，作者通过全基因组关联分析鉴定到了9个与黄光果刺密度相关的遗传位点。在这9个位点中，fsdG2.1基因与典型的ns遗传位点关系最为密切，fsdG2.1位点包含一个候选基因Csa2G264590。

结果2-过表达与敲除：Overexpression of Csa2G264590 resulted in lower fruit spine density, and the knockout mutant generated by CRISPR/Cas9 displayed an increased spine density, demonstrating that the Csa2G264590 gene is NS. 

过表达Csa2G264590基因会导致果刺密度降低，而通过CRISPR/Cas9技术敲除Csa2G264590基因则会导致果刺密度增加，表明Csa2G264590基因就是NS基因。

结果3-表达模式与作用途径：NS is specifically expressed in the fruit peel and spine. Genetic analysis showed that NS regulates fruit spine development independently of the tuberculate gene, Tu, which regulates spine development on tubercules; the cucumber glabrous mutants csgl1 and csgl3 are epistatic to ns. 

NS基因在果皮和果刺中特异性表达。遗传分析显示NS基因调控果刺的发育，并且独立于果瘤基因Tu，Tu基因在果瘤中调控刺的发育；并且，黄瓜五毛突变体csgl1和csgl3对于ns基因是上位性的。

结果4-生长素：Furthermore, we found that auxin levels in the fruit peel and spine were significantly lower in the knockout mutant ns-cr. Moreover, RNA-seq showed that the plant hormone signal transduction pathway was enriched. Notably, most of the auxin responsive Aux/IAA family genes were down-regulated in ns-cr. 

此外，作者发现在NS基因敲除突变体ns-cr中，果皮和果刺中的生长素水平显著降低。另外，RNA-seq显示富集到了植物激素信号转导通路。有趣的是，大多数的生长素响应Aux/IAA家族基因在ns-cr中表达量显著下调。

结果5-单倍型分析：Haplotype analysis showed that the nonfunctional haplotype of NS exists exclusively in the Eurasian cucumber backgrounds.

单倍型分析显示，NS的非功能性单倍体广泛存在于欧亚黄瓜种质中。

结论：Taken together, the cloning of NS gene provides new insights into the regulatory network of fruit spine development.

综上，对于NS基因的成功克隆为黄瓜果刺的调控网络提供了新的视野。

** 张圣平 **

doi: https://doi.org/10.1111/tpj.15710

Journal: the plant journal

Published date: February 19, 2022