Severe environments disturb the folding or assembly of newly synthesized proteins, resulting in accumulation of misfolded or unfolded proteins in the endoplasmic reticulum (ER) as well as cytotoxic aggregation of abnormal proteins. Therefore, ER stress is evoked due to disturbed ER homeostasis. Alternative oxidase (AOX) plays an important role in coping with various abiotic stresses and plant growth. Our previous study has reported that PpAOX is involved in the regulation of salt tolerance in moss Physcomitrella patens (P. patens), but its biological functions in modulating ER stress remain unknown. Here we report that the gametophyte of P. patens displays severe growth inhibition and developmental deficiency under tunicamycin (Tm, an elicitor of ER stress)-induced ER stress conditions. PpAOX and selected ER stress response-like genes in P. patens were induced under Tm treatment. PpAOX knockout (PpAOX KO) plants exhibited decreased resistance to Tm-induced ER stress, whereas PpAOX-overexpressing lines (PpAOX OX) plants were more tolerant to Tm-induced ER stress. Data showed that PpAOX contributes to redox homeostasis under Tm treatment. In addition, we observed that PpAOX completely restores the Tm-sensitive phenotype of Arabidopsis AOX1a mutant (Ataox1a). Taken together, our work reveals a functional link between PpAOX and ER stress tolerance regulation in P. patens.

中文翻译：

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PpAOX 调节 Physcomitrella patens 的 ER 胁迫耐受性

恶劣的环境会干扰新合成蛋白质的折叠或组装，导致错误折叠或未折叠蛋白质在内质网 (ER) 中的积累以及异常蛋白质的细胞毒性聚集。因此，ER 应激是由于 ER 稳态紊乱引起的。替代氧化酶（AOX）在应对各种非生物胁迫和植物生长方面发挥着重要作用。我们之前的研究报道，PpAOX 参与调节苔藓 Physcomitrella patens (P. patens) 的耐盐性，但其在调节内质网应激方面的生物学功能仍然未知。在这里我们报告说，P. patens 的配子体在衣霉素（Tm，ER 应激的引发剂）诱导的 ER 应激条件下显示出严重的生长抑制和发育缺陷。PpAOX 和选定的 ER 应激反应样基因在 P. 在 Tm 处理下诱导了专利。PpAOX 敲除 (PpAOX KO) 植物对 Tm 诱导的 ER 胁迫的抗性降低，而 PpAOX 过表达系 (PpAOX OX) 植物对 Tm 诱导的 ER 胁迫更耐受。数据显示 PpAOX 在 Tm 处理下有助于氧化还原稳态。此外，我们观察到 PpAOX 完全恢复了拟南芥 AOX1a 突变体（Ataox1a）的 Tm 敏感表型。总之，我们的工作揭示了 PpAOX 和 P. patens ER 应激耐受调节之间的功能联系。我们观察到 PpAOX 完全恢复了拟南芥 AOX1a 突变体（Ataox1a）的 Tm 敏感表型。总之，我们的工作揭示了 P. patens 中 PpAOX 和 ER 应激耐受调节之间的功能联系。我们观察到 PpAOX 完全恢复了拟南芥 AOX1a 突变体（Ataox1a）的 Tm 敏感表型。总之，我们的工作揭示了 P. patens 中 PpAOX 和 ER 应激耐受调节之间的功能联系。