Abstract：
Stress tolerance in apple (Malus domestica) can be improved by grafting to a stress-tolerant rootstock, such as \'SH6\' (Malus honanensis × M. domestica \'Ralls Genet\'). However, the mechanisms of stress tolerance in this rootstock are unclear. In Arabidopsis (Arabidopsis thaliana), the transcription factor ZINC FINGER OF ARABIDOPSIS THALIANA 10 (ZAT10) is a key component of plant tolerance to multiple abiotic stresses and positively regulates antioxidant enzymes. However, how reactive oxygen species (ROS) are eliminated upon activation of ZAT10 in response to abiotic stress remains elusive. Here, we report that MhZAT10 in the rootstock SH6 directly activates the transcription of three genes encoding the antioxidant enzymes MANGANESE SUPEROXIDE DISMUTASE 1 (MhMSD1), ASCORBATE PEROXIDASE 3A (MhAPX3a), and CATALASE 1 (MhCAT1) by binding to their promoters. Heterologous expression in Arabidopsis protoplasts showed that MhMSD1, MhAPX3a, and MhCAT1 localize in multiple subcellular compartments. Overexpressing MhMSD1, MhAPX3a, or MhCAT1 in SH6 fruit calli resulted in higher superoxide dismutase, ascorbate peroxidase, and catalase enzyme activities in their respective overexpressing calli than in those overexpressing MhZAT10. Notably, the calli overexpressing MhZAT10 exhibited better growth and lower ROS levels under simulated osmotic stress. Apple SH6 plants overexpressing MhZAT10 in their roots via Agrobacterium rhizogenes-mediated transformation also showed enhanced tolerance to osmotic stress, with higher leaf photosynthetic capacity, relative water content in roots, and antioxidant enzyme activity, as well as less ROS accumulation. Overall, our study demonstrates that the transcription factor MhZAT10 synergistically regulates the transcription of multiple antioxidant-related genes and elevates ROS detoxification.
摘要：
苹果（Malusdomestica）的抗逆性可以通过嫁接到抗逆性砧木上来提高，如“SH6”(苹果红土×M.domestica\“RallsGenet”)。然而,这种砧木的抗逆机制尚不清楚。在拟南芥（拟南芥）中，拟南芥的转录因子锌指10（ZAT10）是植物对多种非生物胁迫的耐受性的关键成分，并积极调节抗氧化酶。然而,在响应非生物胁迫时，如何在激活ZAT10时消除活性氧（ROS）仍然难以捉摸。这里,我们报告说，砧木SH6中的MhZAT10直接激活三个编码抗氧化酶锰超氧化物歧化酶1（MhMSD1）的基因的转录，抗坏血酸过氧化物酶3A(MhAPX3a)，和过氧化氢酶1(MhCAT1)通过结合到它们的启动子。在拟南芥原生质体中的异源表达表明MhMSD1、MhAPX3a、和MhCAT1定位在多个亚细胞区室中。超压MhMSD1、MhAPX3a、或SH6果实愈伤组织中的MHCAT1导致更高的超氧化物歧化酶，抗坏血酸过氧化物酶，和各自过表达的愈伤组织中的过氧化氢酶活性比过表达MhZAT10的愈伤组织中的过氧化氢酶活性。值得注意的是,在模拟渗透胁迫下，过表达MhZAT10的愈伤组织表现出更好的生长和较低的ROS水平。通过发根农杆菌介导的转化在其根中过表达MhZAT10的苹果SH6植物也显示出对渗透胁迫的耐受性增强，具有较高的叶片光合能力，根中的相对含水量，和抗氧化酶活性，以及较少的ROS积累。总的来说,我们的研究表明，转录因子MhZAT10协同调节多个抗氧化相关基因的转录，并提高ROS解毒。
