IntroductionSainfoin (Onobrychis viciaefolia) is a vital legume forage, and drought is the primary element impeding sainfoin growth.ObjectiveThe anatomical structure, physiological indexes, and metabolites of the leaves of sainfoin seedlings with a drought‐resistant line of P1 (DRL) and a drought‐sensitive material of 2049 (DSM) were analyzed under drought (−1.0 MPa) with polyethylene glycol‐6000 (PEG‐6000).MethodsThe leaf anatomy was studied by the paraffin section method. The related physiological indexes were measured by the hydroxylamine oxidation method, titanium sulfate colorimetric method, thiobarbituric acid method, acidic ninhydrin colorimetric method, and Coomassie brilliant blue method. The metabolomics analysis was composed of liquid chromatography tandem high‐resolution mass spectrometry (LC‐MS/MS).ResultsThe results revealed that the thickness of the epidermis, palisade tissue, and sponge tissue of DRL were significantly greater than those of DSM. The leaves of DRL exhibited lower levels of superoxide anion (O2•−) production rate, hydrogen peroxide (H2O2) content, and malondialdehyde (MDA) content compared with DSM, while proline (Pro) content and soluble protein (SP) content were significantly higher than those of DSM. A total of 391 differential metabolites were identified in two samples. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment showed that the primary differential metabolites were concentrated into the tyrosine metabolism; isoquinoline alkaloid biosynthesis; ubiquinone and other terpenoid quinone biosynthesis; neomycin, kanamycin, and gentamicin biosynthesis; and anthocyanin biosynthesis metabolic pathways.ConclusionCompared with DSM, DRL had more complete anatomical structure, lower active oxygen content, and higher antioxidant level. The results improved our insights into the drought‐resistant mechanisms in sainfoin.

中文翻译：

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综合叶片解剖结构、生理学和代谢组分析揭示了红豆苗期对干旱胁迫的反应

简介 Sainfoin (红豆草红豆是重要的豆科牧草，干旱是阻碍红豆生长的首要因素。 目的研究红豆抗旱品系P1（DRL）和干旱敏感材料红豆幼苗叶片的解剖结构、生理指标及代谢产物。在干旱（-1.0 MPa）下用聚乙二醇-6000（PEG-6000）对2049（DSM）进行分析。方法采用石蜡切片法研究叶片解剖结构。采用羟胺氧化法、硫酸钛比色法、硫代巴比妥酸法、酸性茚三酮比色法、考马斯亮蓝法测定相关生理指标。代谢组学分析采用液相色谱串联高分辨率质谱（LC-MS/MS）。结果结果显示，DRL的表皮、栅栏组织和海绵组织的厚度均显着大于DSM。 DRL 的叶子表现出较低水平的超氧阴离子 (O2•−) 产率，过氧化氢 (H2氧2)含量、丙二醛(MDA)含量与DSM相比，而脯氨酸(Pro)含量和可溶性蛋白(SP)含量显着高于DSM。两个样品中总共鉴定出 391 种差异代谢物。京都基因与基因组百科全书（KEGG）富集显示，初级差异代谢物集中在酪氨酸代谢；异喹啉生物碱生物合成；泛醌和其他萜醌的生物合成；新霉素、卡那霉素和庆大霉素的生物合成；结论与DSM相比，DRL具有更完整的解剖结构、更低的活性氧含量、更高的抗氧化水平。这些结果提高了我们对红枫抗旱机制的认识。