State Key Laboratory of Crop Stress Biology for Arid Areas/Shaanxi Key Laboratory of Apple, College of Horticulture, Northwest A&F University, Yangling, 712100, Shaanxi, China.
Center of Pear Engineering Technology Research, State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Horticulture, Nanjing Agricultural University, Nanjing, 210095, China.
Plant Sci. 2021 Nov;312:111052. doi: 10.1016/j.plantsci.2021.111052. Epub 2021 Sep 6.
Drought occurrence seriously affects the productivity and quality of apple crop worldwide. Autophagy, a conserved process for the degradation and recycling of unwanted cellular components, is considered to positively regulate the tolerance of various abiotic stresses in plants. In the current study, we isolated two ATG5 homologs genes, namely, MdATG5a and MdATG5b, from apple, demonstrating their responsiveness to drought and oxidative stresses. In addition to having the same cellular localization in the nucleus and cytoplasm, both MdATG5a and MdATG5b could interact with MdATG12. Transgenic apple plants overexpressing MdATG5a exhibited an improved drought tolerance, as indicated by less drought-related damage and higher photosynthetic capacities compared to wild-type (WT) plants under drought stress. The overexpression of MdATG5a improved antioxidant defenses in apple when exposed to drought via elevating both antioxidant enzyme activities and the levels of beneficial antioxidants. Furthermore, under drought stress, the overexpression of MdATG5a promoted the mobilization of starch to accumulate greater levels of soluble sugars, contributing to osmotic adjustments and supporting carbon skeletons for proline synthesis. Such changes in physiological responses may be associated with increased autophagic activities in the transgenic plants upon exposure to drought. Our results demonstrate that MdATG5a-mediated autophagy enhances drought tolerance of apple plants via improving antioxidant defenses and metabolic adjustments.
干旱的发生严重影响了全球苹果作物的生产力和品质。自噬是一种用于降解和回收不需要的细胞成分的保守过程，被认为可以积极调节植物对各种非生物胁迫的耐受性。在本研究中，我们从苹果中分离出两个 ATG5 同源基因，即 MdATG5a 和 MdATG5b，证明它们对干旱和氧化胁迫有反应。除了在细胞核和细胞质中有相同的细胞定位外，MdATG5a 和 MdATG5b 都可以与 MdATG12 相互作用。与野生型（WT）植物相比，过表达 MdATG5a 的转基因苹果植物在干旱胁迫下表现出更好的耐旱性，表现为与干旱相关的损伤减少和更高的光合作用能力。过表达 MdATG5a 通过提高抗氧化酶活性和有益抗氧化剂水平，在苹果暴露于干旱时改善了抗氧化防御。此外，在干旱胁迫下，过表达 MdATG5a 促进淀粉向可溶性糖的积累，从而有助于渗透调节并为脯氨酸合成提供碳骨架。这些生理反应的变化可能与干旱胁迫下转基因植物中自噬活性的增加有关。我们的结果表明，MdATG5a 介导的自噬通过改善抗氧化防御和代谢调节来增强苹果植物的耐旱性。
