The evolutionary success of plants relies to a large extent on their extraordinary ability to adapt to changes in their environment. These adaptations require that plants balance their growth with their stress responses. Plant hormones are crucial mediators orchestrating the underlying adaptive processes. However, whether and how the growth-related hormone auxin and the stress-related hormones jasmonic acid, salicylic acid, and abscisic acid (ABA) are coordinated remains largely elusive. Here, we analyse the physiological role of AMIDASE 1 (AMI1) in Arabidopsis plant growth and its possible connection to plant adaptations to abiotic stresses. AMI1 contributes to cellular auxin homeostasis by catalysing the conversion of indole-acetamide into the major plant auxin indole-3-acetic acid. Functional impairment of AMI1 increases the plant’s stress status rendering mutant plants more susceptible to abiotic stresses. Transcriptomic analysis of ami1 mutants disclosed the reprogramming of a considerable number of stress-related genes, including jasmonic acid and ABA biosynthesis genes. The ami1 mutants exhibit only moderately repressed growth but an enhanced ABA accumulation, which suggests a role for AMI1 in the crosstalk between auxin and ABA. Altogether, our results suggest that AMI1 is involved in coordinating the trade-off between plant growth and stress responses, balancing auxin and ABA homeostasis.

中文翻译：

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内源吲哚-3-乙酰胺水平促进生长素和脱落酸之间的串扰，并触发拟南芥中的植物胁迫反应

植物的进化成功在很大程度上取决于其适应环境变化的非凡能力。这些适应要求植物平衡其生长与胁迫响应。植物激素是协调潜在适应过程的关键介质。然而，与生长相关的激素生长素和与压力相关的激素茉莉酸，水杨酸和脱落酸（ABA）是否协调以及如何协调仍然很遥远。在这里，我们分析了酰胺酶1（AMI1）在拟南芥植物生长中的生理作用及其与植物适应非生物胁迫的可能联系。AMI1通过催化吲哚-乙酰胺转化为主要的植物生长素吲哚-3-乙酸来促进细胞生长素的稳态。AMI1的功能受损增加了植物的胁迫状态，使突变植物更容易遭受非生物胁迫。转录组学分析ami1突变体披露了许多与应激相关的基因的重编程，包括茉莉酸和ABA生物合成基因。该ami1突变表现出只有适度抑制生长，但增强ABA的积累，这表明了在AMI1生长素和ABA之间的串扰的作用。总之，我们的结果表明AMI1参与协调植物生长与胁迫反应之间的权衡，平衡植物生长素和ABA的稳态。