Zhang Weiyi, Alseekh Saleh, Zhu Xiang, Zhang Qinghua, Fernie Alisdair R, Kuang Hanhui, Wen Weiwei
Key Laboratory of Horticultural Plant Biology (MOE), College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan, 430070, China.
Max-Planck-Institute of Molecular Plant Physiology, Am Muehlenberg 1, Potsdam-Golm, 14476, Germany.
Plant J. 2020 Nov;104(3):613-630. doi: 10.1111/tpj.14950. Epub 2020 Sep 14.
Lettuce (Lactuca sativa L.) is an important vegetable crop species worldwide. The primary metabolism of this species is essential for its growth, development and reproduction as well as providing a considerable direct source of energy and nutrition for humans. Here, through investigating 77 primary metabolites in 189 accessions including all major horticultural types and wild lettuce L. serriola we showed that the metabolites in L. serriola were different from those in cultivated lettuce. The findings were consistent with the demographic model of lettuce and supported a single domestication event for this species. Selection signals among these metabolic traits were detected. Specifically, galactinol, malate, quinate and threonate were significantly affected by the domestication process and cultivar differentiation of lettuce. Galactinol and raffinose might have been selected during stem lettuce cultivation as an adaption to the local environments in China. Furthermore, we identified 154 loci significantly associated with the level of 51 primary metabolites. Three genes (LG8749721, LG8763094 and LG5482522) responsible for the levels of galactinol, raffinose, quinate and chlorogenic acid were further dissected, which may have been the target of domestication and/or affected by local adaptation. Additionally, our findings strongly suggest that human selection resulted in reduced quinate and chlorogenic acid levels in cultivated lettuce. Our study thus provides beneficial genetic resources for lettuce quality improvement and sheds light on the domestication and evolution of this important leafy green.
生菜（Lactuca sativa L.）是全球重要的蔬菜作物品种。该物种的初级代谢对其生长、发育和繁殖至关重要，同时也为人类提供了相当可观的直接能量和营养来源。在此，通过对189份材料（包括所有主要园艺类型和野生生菜L. serriola）中的77种初级代谢物进行研究，我们发现L. serriola中的代谢物与栽培生菜中的不同。这些发现与生菜的人口统计学模型一致，并支持该物种的单次驯化事件。检测到这些代谢性状之间的选择信号。具体而言，半乳糖醇、苹果酸、奎尼酸和苏糖酸受生菜驯化过程和品种分化的影响显著。半乳糖醇和棉子糖可能在茎用生菜栽培过程中被选择，以适应中国的当地环境。此外，我们鉴定出154个与51种初级代谢物水平显著相关的位点。进一步剖析了负责半乳糖醇、棉子糖、奎尼酸和绿原酸水平的三个基因（LG8749721、LG8763094和LG5482522），它们可能是驯化的目标和/或受当地适应性影响。此外，我们的研究结果强烈表明，人工选择导致栽培生菜中奎尼酸和绿原酸水平降低。因此我们为生菜品质改良提供了有益的遗传资源，并揭示了这种重要叶菜类蔬菜的驯化和进化过程。
