Drought stress is one of the most devastating abiotic stresses, compromising crop growth, reproductive success and yield. The arbuscular mycorrhizal (AM) symbiosis has been demonstrated to be beneficial in helping the plant to bear with water deficit. In plants, development and stress responses are largely regulated by a complex hormonal crosstalk. Auxins play significant roles in plant growth and development, in responses to different abiotic stresses or in the establishment and functioning of the AM symbiosis. Despite these important functions, the role of indole-3acetic acid (IAA) as a regulator of root water transport and stress response is not well understood. In this study, the effect of exogenous application of IAA on the regulation of root radial water transport in AM plants was analyzed under well-watered and drought stress conditions. Exogenous IAA application affected root hydraulic parameters, mainly osmotic root hydraulic conductivity (Lo), which was decreased in both AM and non-AM plants under water deficit conditions. Under drought, the relative apoplastic water flow was differentially regulated by IAA application in non-AM and AM plants. The effect of IAA on the internal cell component of root water conductivity suggests that aquaporins are involved in the IAA-dependent inhibition of this water pathway.

中文翻译：

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干旱胁迫条件下丛枝菌根玉米植物的径向水分运输受吲哚乙酸（IAA）施用的影响

干旱胁迫是最具破坏性的非生物胁迫之一，会影响作物生长、繁殖成功和产量。丛枝菌根 (AM) 共生已被证明有利于帮助植物承受水分不足。在植物中，发育和应激反应在很大程度上受复杂的激素串扰调节。生长素在植物生长和发育、对不同非生物胁迫的响应或 AM 共生的建立和功能方面发挥着重要作用。尽管有这些重要的功能，但吲哚-3 乙酸 (IAA) 作为根系水分运输和应激反应的调节剂的作用尚不清楚。在这项研究中，在水分充足和干旱胁迫条件下，分析了外源施用 IAA 对 AM 植物根径向水分输送调节的影响。外源 IAA 应用影响根系水力参数，主要是渗透根水力传导率 (Lo)，在缺水条件下，AM 和非 AM 植物均降低。在干旱条件下，非 AM 和 AM 植物中 IAA 的应用对相对质外体水流量有不同的调节。IAA 对根部水电导率的内部细胞成分的影响表明，水通道蛋白参与了 IAA 依赖性抑制该水通路。