Data Sheet 1_StACS3-mediated drought stress adaptation in potato involves interactions with StPP2C2 and St14-3-3 proteins.pdf

Ethylene plays a critical role in plant development and stress adaptation, with its biosynthesis tightly regulated by the stability of 1-aminocyclopropane-1-carboxylic acid synthase (ACS) proteins. Here, we investigate the potato isozyme StACS3 and its role in modulating ethylene biosynthesis and drought tolerance. StACS3 transcript and protein levels are specifically upregulated under drought stress. In contrast, silencing StACS3 significantly reduces stress-induced ethylene accumulation and enhances drought resilience, including decreased cell death and increased antioxidant activity. Heterologous expression of StACS3 in Arabidopsis thaliana induces severe developmental phenotypes, such as compact growth, reduced root development, sterility, and accelerated leaf senescence, demonstrating its influence on ethylene-associated processes. Mechanistically, StACS3 is regulated post-translationally through interactions with StPP2C2, a type 2C protein phosphatase that promotes proteasome-mediated degradation, and St14-3-3, a phospho-binding protein that stabilizes StACS3. Mutation and co-expression analysis support the formation of StACS3-StPP2C2 complexes, and silencing StPP2C2 increases StACS3 accumulation and alters its subcellular localization, demonstrating an antagonistic interplay between degradation and stabilization pathways. Collectively, these findings reveal a dynamic post-translational regulatory module that fine-tunes ethylene biosynthesis during drought stress. This study establishes StACS3 as a central node in ethylene-mediated drought response pathways in potatoes, providing mechanistic insights into the balance of protein degradation and stabilization that underlies stress adaptation.

乙烯在植物生长发育与胁迫适应中发挥关键作用，其生物合成严格受1-氨基环丙烷-1-羧酸合酶（1-aminocyclopropane-1-carboxylic acid synthase, ACS）的蛋白稳定性调控。本研究聚焦马铃薯同工酶StACS3，探究其在调控乙烯生物合成与耐旱性中的功能。干旱胁迫下，StACS3的转录与蛋白水平特异性上调。与之相反，沉默StACS3可显著降低胁迫诱导的乙烯积累，并提升植株耐旱性，具体表现为细胞死亡减少、抗氧化活性增强。将StACS3在拟南芥（Arabidopsis thaliana）中进行异源表达，会引发严重的发育表型，包括生长紧凑、根系发育受阻、育性低下以及叶片早衰，证实其参与乙烯相关生理过程。机制层面，StACS3通过与两类蛋白的相互作用受到翻译后调控：一类是2C型蛋白磷酸酶StPP2C2，可促进蛋白酶体介导的StACS3降解；另一类是磷酸结合蛋白St14-3-3，能够稳定StACS3。突变与共表达分析证实了StACS3-StPP2C2复合物的形成，而沉默StPP2C2会增加StACS3的积累量并改变其亚细胞定位，表明降解与稳定通路之间存在拮抗互作。综上，本研究揭示了一个动态的翻译后调控模块，可在干旱胁迫期间精细调控乙烯生物合成。本研究确立了StACS3作为马铃薯乙烯介导干旱应答通路的核心节点，为解析胁迫适应背后的蛋白降解与稳定平衡机制提供了新见解。