Salt stress reduces crop growth and productivity globally. Here we report that a R2R3‐MYB transcription factor MYB30 participates in salt tolerance in Arabidopsis. MYB30 can be SUMOylated by SIZ1 in response to salt stress and the lysine (K)283 of MYB30 is essential for its SUMOylation. In contrast to wild‐type MYB30, the MYB30^K283R mutant failed to rescue the salt‐sensitive phenotype of the myb30‐2 mutant, indicating that SUMOylation of MYB30 is required for the salt‐stress response. Through transcriptomic analysis, we identified a MYB30 target, alternative oxidase 1a (AOX1a ). MYB30 binds the promoter of AOX1a and upregulates its expression in response to salt stress; however, MYB30^K283R cannot bind the promoter of AOX1a . The cyanide (CN)‐resistant alternative respiration (Alt) mediated by AOX is significantly reduced in the myb30‐2 mutant through the loss of function of MYB30. As a result, the redox homeostasis is disrupted in the myb30‐2 mutant compared with that in wild‐type seedlings (WT) under salt conditions. The artificial elimination of excess reactive oxygen species partially rescues the salt‐sensitive phenotype of the myb30 ‐2 mutant, whereas after the exogenous application of SHAM, an inhibitor of AOXs and Alt respiration, the salt tolerance of Col‐0 and the complemented plants decreased to a level similar to that observed in myb30‐2 . Finally, overexpression of AOX1a in myb30‐2 confers WT‐like salt tolerance compared with that of the myb30‐2 mutant. Taken together, our results revealed a functional link between MYB30 and AOX1a, and indicated that SIZ1‐mediated SUMOylation of MYB30 enhances salt tolerance by regulating Alt respiration and cellular redox homeostasis via AOX1a in Arabidopsis.

中文翻译：

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MYB30的SUMOylation通过在拟南芥中通过转录上调AOX1a来提高替代呼吸来增强耐盐性。

盐胁迫降低了全球作物的生长和生产力。在这里，我们报道R2R3-MYB转录因子MYB30参与拟南芥的耐盐性。SIB1可以对盐胁迫进行SUMO酰化MYB30，而MYB30的赖氨酸（K）283对于SUMO酰化至关重要。与野生型MYB30相比，MYB30 ^K283R突变体^{无法挽救myb30-2}突变体的盐敏感性表型，表明盐胁迫响应需要MYB30的SUMOylation。通过转录组分析，我们确定了MYB30靶标，替代氧化酶1a（AOX1a）。MYB30结合AOX1a的启动子并响应盐胁迫而上调其表达。但是，MYB30 ^K283R不能结合AOX1a的启动子。通过MYB30的功能丧失，在myb30-2突变体中，由AOX介导的抗氰化物（CN）的替代呼吸（Alt）显着降低。结果，与盐条件下的野生型幼苗（WT）相比，myb30-2突变体中的氧化还原稳态被破坏了。人工消除过量的活性氧会部分拯救myb30-2突变体的盐敏感性表型，而在外源应用SHAM后，AOXs和Alt呼吸的抑制剂，Col-0和互补植物的耐盐性下降达到类似于myb30-2中观察到的水平。最后，AOX1a的过度表达与myb30-2突变体相比，myb30-2具有类似WT的耐盐性。综上所述，我们的结果揭示了MYB30和AOX1a之间的功能联系，并表明SIZ1介导的MYB30的SUMOylation通过调节拟南芥中的Alt呼吸和经由AOX1a的细胞氧化还原稳态来增强盐耐受性。