• Plants maintain a dynamic balance between plant growth and stress tolerance to optimise their fitness and ensure survival. Here, we investigated the roles of a clade A type 2C protein phosphatase (PP2C)‐encoding gene, OsPP2C09 , in regulating the trade‐off between plant growth and drought tolerance in rice (Oryza sativa L.).
• The OsPP2C09 protein interacted with the core components of abscisic acid (ABA) signalling and showed PP2C phosphatase activity in vitro . OsPP2C09 positively affected plant growth but acted as a negative regulator of drought tolerance through ABA signalling.
• Transcript and protein levels of OsPP2C09 were rapidly induced by exogenous ABA treatments, which suppressed excessive ABA signalling and plant growth arrest. OsPP2C09 transcript levels in roots were much higher than those in shoots under normal conditions. After ABA, polyethylene glycol and dehydration treatments, the accumulation rate of OsPP2C09 transcripts in roots was more rapid and greater than that in shoots. This differential expression between the roots and shoots may increase the plant’s root‐to‐shoot ratio under drought‐stress conditions.
• This study sheds new light on the roles of OsPP2C09 in coordinating plant growth and drought tolerance. In particular, we propose that OsPP2C09‐mediated ABA desensitisation contributes to root elongation under drought‐stress conditions in rice.

中文翻译：

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OsPP2C09是脱落酸信号的负调控因子，在平衡水稻的植物生长和抗旱性中起着至关重要的作用。

• 植物在植物生长和胁迫耐受性之间保持动态平衡，以优化其适应性并确保生存。在此，我们研究了进化枝A型2C蛋白磷酸酶（PP2C）编码基因OsPP2C09在调节水稻（Oryza sativa L.）植物生长与干旱耐受性之间的权衡作用。
• OsPP2C09蛋白与脱落酸（ABA）信号转导的核心成分相互作用，并在体外显示PP2C磷酸酶活性。OsPP2C09正面影响植物生长，但通过ABA信号转导充当抗旱性的负调节剂。
• 外源ABA处理可迅速诱导OsPP2C09的转录本和蛋白质水平，从而抑制了过量的ABA信号传导和植物生长停滞。在正常条件下，根中的OsPP2C09转录水平远高于芽中的水平。经过ABA，聚乙二醇和脱水处理后，OsPP2C09转录本在根中的积累速率比芽中的积累更快，更大。在干旱胁迫条件下，根与芽之间的这种差异表达可能会增加植物的根茎比。
• 这项研究为OsPP2C09在协调植物生长和抗旱性中的作用提供了新的思路。特别是，我们提出OsPP2C09介导的ABA脱敏作用有助于水稻在干旱胁迫条件下的根伸长。