Abstract Saline conditions can significantly affect plant growth and development, leading to massive reduction in crop yield. Herein, we show that a protein repairing enzyme PROTEIN l -ISOASPARTYL METHYLTRANSFERASE imparts salinity stress tolerance in Arabidopsis thaliana by repairing deleterious isoAsp accumulation during salinity stress. We demonstrate that salinity stress accelerates isoAsp accumulation in proteins and also induces PIMT activity in Arabidopsis. Transcript analysis indicates that both PIMT1 and PIMT2 are upregulated in response to salinity stress. Subsequent functional analysis reveals that PIMT1 and PIMT2 overexpression lines are tolerant, while RNAi lines are hyper sensitive to salinity stress in comparison to wild type (WT). Biochemical analyses of thesePIMT transgenic lines also reveals that compromised salinity tolerance of RNAi lines are linked to increased isoAsp accumulation, while improved tolerance of overexpression lines is associated with reduced isoAsp accumulation in proteins. Histochemical and biochemical studies further confirm lower accumulation of ROS and reduced lipid peroxidation in PIMT overexpression lines, while increased ROS accumulation and increased lipid peroxidation in RNAi lines as compared to WT under salinity stress. Interestingly, PIMToverexpression lines exhibit improved antioxidant enzyme efficiency, while RNAi lines display compromised antioxidant enzyme efficacy as compared to WT type plants. Our study suggests that PIMT improves salinity stress tolerance by restricting salt induced-excess ROS accumulation possibly by repairing isoAsp mediated protein damage of antioxidant enzymes. Our study can be utilized for enhancing salinity stress tolerance of economically important crops.

中文翻译：

---

蛋白质修复酶 PROTEIN L-ISOASPARTYL METHYLTRANSFERASE 通过提高 ROS 清除酶的效率参与盐胁迫耐受性

摘要 盐分条件会显着影响植物的生长发育，导致作物产量大幅下降。在此，我们展示了蛋白质修复酶 PROTEIN l -ISOASPARTYL METHYLTRANSFERASE 通过修复盐胁迫期间有害的 isoAsp 积累，赋予拟南芥盐胁迫耐受性。我们证明盐度胁迫加速了蛋白质中 isoAsp 的积累，并且还诱导了拟南芥中的 PIMT 活性。转录分析表明 PIMT1 和 PIMT2 都响应于盐度胁迫而上调。随后的功能分析表明，与野生型 (WT) 相比，PIMT1 和 PIMT2 过表达系具有耐受性，而 RNAi 系对盐度胁迫高度敏感。这些 PIMT 转基因品系的生化分析还表明，RNAi 品系的耐盐性受损与 isoAsp 积累增加有关，而过表达品系的耐受性提高与蛋白质中 isoAsp 积累减少有关。组织化学和生化研究进一步证实，与盐胁迫下的 WT 相比，PIMT 过表达系中 ROS 的积累较低，脂质过氧化减少，而 RNAi 系中 ROS 积累增加，脂质过氧化增加。有趣的是，与 WT 型植物相比，PIMT 过表达株系表现出提高的抗氧化酶效率，而 RNAi 株系表现出受损的抗氧化酶效率。我们的研究表明，PIMT 可能通过修复 isoAsp 介导的抗氧化酶的蛋白质损伤来限制盐诱导的过量 ROS 积累，从而提高盐胁迫耐受性。我们的研究可用于提高重要经济作物的盐胁迫耐受性。