Mitochondrial homeostasis plays a crucial role in determining cell fate by direct influence on cell apoptosis and autophagy. The ATP and Zn²⁺-dependent protease FtsH are of paramount importance in maintaining mitochondrial homeostasis. In Phalaenopsis equestris, three mitochondrial FtsH proteases were identified, one of which was encoded by the PeFtsH5 gene. This gene encoded a distinctive mitochondrial protein featuring a unique domain within the FtsH family. Down-regulating the expression of the PeFtsH5 homolog in Nicotiana benthamiana resulted in elevated expression levels of SA synthesis-related genes, leading to enhanced disease resistance. However, this down-regulation also caused cellular damage. Similarly, in P. equestris, the down-regulation of PeFtsH5 expression promoted the expression of defense response genes, leading to accelerated apoptosis and increased ROS levels. Nonetheless, this down-regulation also positively influenced plant resistance to biotic stress. Notably, the PeFtsH5 (i-AAA) protein, as revealed by dual membrane experiments, could form homopolymers exclusively, as it did not interact with the other two mitochondrial FtsH proteases. Consequently, this mitochondrial FtsH protease functioned as a homopolymer within P. equestris cells. The findings of this study elucidated the role of PeFtsH5 in responding to biological stress and provided new insights into its potential molecular mechanism. The result presented in this study hold promise for future research endeavors examining the regulatory effects of mitochondrial proteases on mitochondrial homeostasis and the development of stress-resistant P. equestris varieties through breeding programs.

线粒体稳态通过直接影响细胞凋亡和自噬，在决定细胞命运方面发挥着至关重要的作用。ATP 和 Zn ²⁺依赖性蛋白酶 FtsH 对于维持线粒体稳态至关重要。在蝴蝶兰中，鉴定出三种线粒体 FtsH 蛋白酶，其中一种由PeFtsH5基因编码。该基因编码一种独特的线粒体蛋白，具有FtsH家族中的独特结构域。下调本塞姆氏烟草中PeFtsH5同源物的表达会导致 SA 合成相关基因的表达水平升高，从而增强抗病性。然而，这种下调也导致了细胞损伤。同样，在马术中，PeFtsH5表达的下调促进了防御反应基因的表达，导致细胞凋亡加速和 ROS 水平增加。尽管如此，这种下调也对植物对生物胁迫的抵抗力产生积极影响。值得注意的是，双膜实验表明，PeFtsH5 (i-AAA) 蛋白可以专门形成均聚物，因为它不与其他两种线粒体 FtsH 蛋白酶相互作用。因此，这种线粒体 FtsH 蛋白酶在马术细胞内以均聚物的形式发挥作用。这项研究的结果阐明了PeFtsH5在响应生物应激中的作用，并为其潜在的分子机制提供了新的见解。这项研究中提出的结果为未来的研究工作带来了希望，即检查线粒体蛋白酶对线粒体稳态的调节作用以及通过育种计划开发抗压马术品种。