PDF(Pubmed)
Abstract：
Xishuangbanna (XIS) cucumber (Cucumis sativus L. var. xishuangbannanesis) is a semiwild variety originating from low latitude tropic areas, and therefore shows extreme cold sensitivity and heat tolerance. Here, we mapped the quantitative trait loci (QTLs) that control the cold sensitivity and heat tolerance of XIS cucumber seedlings. Using bulked segregant analysis (BSA), we identified three QTLs (HTT1.1, HTT3.1, and HTT3.2, with a total length of 11.98 Mb) for heat tolerance and two QTLs (LTT6.1 and LTT6.2, with a total length of 8.74 Mb) for cold sensitivity. The QTL LTT6.1 was then narrowed down to a length of 641 kb by using kompetitive allele-specific PCR (KASP) markers. Based on structural variants (SVs) and single-nucleotide polymorphisms (SNPs), we found the LTT6.1 is covered by a high divergent region including a 50 kb deletion in the XIS49 genome, which affects the gene structure of lipase abhydrolase domain containing 6 (ABHD6, Csa_6G032560). Accordingly, there is a very big difference in lipid composition, but not in other osmoprotectants like free amino acids and fatty acids, between XIS49 and cultivated cucumber CL. Moreover, we calculated the composite likelihood ratio (CLR) and identified selective sweeps from 115 resequencing data, and found that lipid- and fatty-acid-related processes are major aspects in the domestication of the XIS group cucumber. LTT6.1 is a particularly special region positioned nearby lipid-related selective sweeps. These studies above suggested that the lipid-related domestication of XIS cucumbers should account for their extreme cold sensitivity.
摘要：
西双版纳（XIS）黄瓜（CucumissativusL.var。西双班纳西)是起源于低纬度热带地区的半野生品种，因此表现出极端的冷敏感性和耐热性。这里,我们绘制了控制XIS黄瓜幼苗冷敏感性和耐热性的数量性状位点（QTL）。使用大量分离物分析(BSA)，我们确定了3个耐热QTL(HTT1.1,HTT3.1和HTT3.2,总长度为11.98Mb)和2个冷敏感性QTL(LTT6.1和LTT6.2,总长度为8.74Mb).然后通过使用竞争性等位基因特异性PCR（KASP）标记将QTLLTT6.1缩小到641kb的长度。基于结构变异（SV）和单核苷酸多态性（SNP），我们发现LTT6.1在XIS49基因组中被一个高发散区域覆盖，包括一个50kb的缺失，这影响了含有6（ABHD6，Csa_6G032560）的脂肪酶水解酶结构域的基因结构。因此，脂质成分有很大的差异，但在其他渗透保护剂如游离氨基酸和脂肪酸中却没有，在XIS49和栽培黄瓜CL之间。此外，我们计算了复合似然比(CLR)，并从115个重测序数据中确定了选择性扫描，并发现与脂质和脂肪酸相关的过程是XIS组黄瓜驯化的主要方面。LTT6.1是位于脂质相关选择性扫描附近的特别特殊的区域。上述研究表明，XIS黄瓜的脂质相关驯化应解释其极端寒冷的敏感性。
