Abstract: In order to clarify the metabolic changes of Alfalfa leaves under drought stress,screen and identify the substances that affect leaf transpiration and stomatal movement to provide a theoretical basis for the development of alfalfa stomatal agents,this study used ultra-high performance liquid chromatography-tandem mass spectrometry to determine the metabolome of Alfalfa Medicago sativa L.‘Ladak⁺’ leaves with different degrees of dehydration;and the effects of exogenous differential metabolites on transpiration and stomatal aperture of alfalfa were also analyzed. The results showed that under dehydration stress,carbon and nitrogen metabolism in alfalfa leaves was imbalanced;the content of abscisic acid and callus acid increased significantly,the enhanced glutathione cycle and significant accumulation of osmoregulation substances raised the abilities of alfalfa on antioxidation and osmoregulation. Exogenous was able to promote the stomatal closure of alfalfa leaves,and raffinose and ABA had a synergistic effect on promoting ABA induced stomatal closure. The pyridoxine (VB₆) was able to promote stomatal opening,and it had an antagonistic effect with ABA,inhibiting ABA induced stomatal closure. In conclusion,the drought caused changes of the contents of various metabolites in alfalfa leaves,among which raffinose and VB₆ had regulatory effects on the stomatal movement of alfalfa leaves.

Key words: Metabolomics, Dehydration stress, Stomatal regulation, Alfalfa, Abscisic acid

摘要： 为阐明干旱胁迫下紫花苜蓿叶片的代谢变化,筛选并鉴定影响叶片蒸腾和气孔的物质为开发苜蓿气孔剂提供理论依据,本研究采用超高效液相色谱串联质谱法对不同程度脱水胁迫处理的紫花苜蓿'雷达克之星'(Medicago sativa L. 'Ladak⁺')叶片进行代谢组测定,分析外源差异代谢物对苜蓿蒸腾和气孔开度的影响。结果表明,干旱导致苜蓿叶片碳氮代谢失衡,脱落酸、愈伤酸含量显著增加,谷胱甘肽循环增强和渗透调节物质明显积累使苜蓿的抗氧化能力和渗透调节能力提高。外源棉子糖能够促进紫花苜蓿叶片气孔关闭,并且棉子糖与脱落酸有协同作用,促进脱落酸诱导的气孔关闭;维生素B₆能够促进气孔打开,并且维生素B₆与脱落酸有拮抗作用,抑制脱落酸诱导的气孔关闭。总之,干旱引起苜蓿叶片中多种代谢物含量变化,其中棉子糖、维生素B₆对苜蓿叶片气孔有调控作用。

关键词: 代谢组, 脱水胁迫, 气孔调节, 紫花苜蓿, 脱落酸