BACKGROUND AND AIMS Rhizomes are key organs for the establishment of perennial grass stands and adaptation to environmental stress. However, mechanisms regulating rhizome initiation and elongation under drought stress and during post-drought recovery remain unclear. The objective of this study is to investigate molecular factors and metabolic processes involved in drought effects and post-drought recovery in rhizome growth in perennial grass species by comparative transcriptomic and proteomic profiling. METHODS Tall fescue (Festuca arundinacea) (B-type rhizome genotype, 'BR') plants were exposed to drought stress and re-watering in growth chambers. The number and length of rhizomes were measured following drought stress and re-watering. Hormone and sugar content were analyzed, and transcriptomic and proteomic analyses were performed to identify metabolic factors, genes and proteins associated with rhizome development. KEY RESULTS Rhizome initiation and elongation were inhibited by drought stress, which were associated with increases in the content of abscisic acid (ABA) and soluble sugars, but a decline in the content of indoleacetic acid (IAA), zeatin riboside (ZR) and gibberellin (GA4). Genes involved in multiple metabolic processes and stress defense systems related to rhizome initiation exhibited different responses to drought stress, including ABA signaling, energy metabolism, and stress protection. Drought-inhibition of rhizome elongation could be mainly associated with the alteration of GA4 and antioxidants contents, energy metabolism and stress response proteins. Upon re-watering, new rhizomes were regenerated from rhizome nodes previously exposed to drought stress, which was accompanied by the decline in ABA content and increases in IAA, ZR, and GA4, as well as genes and proteins for auxin, lipids, lignin and nitrogen metabolism. CONCLUSIONS Drought-inhibition of rhizome initiation and elongation in tall fescue was mainly associated with adjustments in hormone metabolism, carbohydrate metabolism and stress-defense systems. Rhizome regeneration in response to re-watering involved reactivation of hormone and lipid metabolism, secondary cell-wall development, and nitrogen remobilization and cycling.

中文翻译：

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多年生草根茎发育抗旱和旱后恢复的差异调控途径

背景和目的 根状茎是建立多年生草丛和适应环境压力的关键器官。然而，在干旱胁迫下和干旱后恢复期间调节根茎起始和伸长的机制仍不清楚。本研究的目的是通过比较转录组学和蛋白质组学分析，研究多年生草种根茎生长的干旱效应和干旱后恢复的分子因素和代谢过程。方法将高羊茅（Festuca arundinacea）（B 型根茎基因型，'BR'）植物暴露于干旱胁迫并在生长室中重新浇水。在干旱胁迫和再浇水后测量根茎的数量和长度。分析了激素和糖含量，进行转录组学和蛋白质组学分析以鉴定与根茎发育相关的代谢因子、基因和蛋白质。主要结果 干旱胁迫抑制了根茎的起始和伸长，这与脱落酸 (ABA) 和可溶性糖含量的增加有关，但与吲哚乙酸 (IAA)、玉米素核苷 (ZR) 和赤霉素含量降低有关(GA4)。参与多种代谢过程和与根茎启动相关的胁迫防御系统的基因对干旱胁迫表现出不同的反应，包括 ABA 信号传导、能量代谢和胁迫保护。干旱抑制根茎伸长可能主要与GA4和抗氧化剂含量、能量代谢和应激反应蛋白的改变有关。重新浇水后，新的根茎从先前暴露于干旱胁迫的根茎节中再生，伴随着 ABA 含量的下降和 IAA、ZR 和 GA4 以及生长素、脂质、木质素和氮代谢的基因和蛋白质的增加。结论 高羊茅根茎起始和伸长的干旱抑制主要与激素代谢、碳水化合物代谢和应激防御系统的调整有关。响应重新浇水的根茎再生涉及激素和脂质代谢的重新激活、次生细胞壁的发育以及氮的再动员和循环。结论 高羊茅根茎起始和伸长的干旱抑制主要与激素代谢、碳水化合物代谢和应激防御系统的调整有关。响应重新浇水的根茎再生涉及激素和脂质代谢的重新激活、次生细胞壁的发育以及氮的再动员和循环。结论 高羊茅根茎起始和伸长的干旱抑制主要与激素代谢、碳水化合物代谢和应激防御系统的调整有关。响应重新浇水的根茎再生涉及激素和脂质代谢的重新激活、次生细胞壁的发育以及氮的再动员和循环。