State Key Laboratory for Crop Stress Resistance and High-Efficiency Production/Shaanxi Key Laboratory of Apple, Pomology Department, College of Horticulture, Northwest A&F University, Yangling, Shaanxi, China.
Plant Cell Environ. 2024 Mar;47(3):751-764. doi: 10.1111/pce.14791. Epub 2024 Jan 2.
High temperatures negatively impact the yield and quality of fruit crops. Exogenous melatonin (MT) application has been shown to enhance heat tolerance, but the response of endogenous MT to heat stress, particularly in perennial fruit trees, remains unclear. The present study investigated the effects of high temperatures on transgenic apple plants overexpressing the MT biosynthesis gene N-acetylserotonin methyltransferase 9 (MdASMT9). Endogenous MT protected transgenic plants from heat stress by increasing antioxidant enzyme activity and scavenging reactive oxygen species (ROS), and protecting the chloroplasts from damage. Application of MT and overexpression of MdASMT9 also reduced abscisic acid accumulation through promoting MdWRKY33-mediated transcriptional inhibition of MdNCED1 and MdNCED3, thus inducing stomatal opening for better heat dissipation. Furthermore, MT-enhanced autophagic activity through promoting MdWRKY33-mediated transcriptional enhancement of MdATG18a under heat stress. These findings provide new insights into the regulation of endogenous MT and its role in improving basal thermotolerance in perennial fruit trees.
高温会降低果实作物的产量和品质。外源褪黑素（MT）的应用已被证明可以提高植物的耐热性，但内源性 MT 对热胁迫的反应，特别是在多年生果树中，仍不清楚。本研究调查了高温对过表达 MT 生物合成基因 N-乙酰血清素甲基转移酶 9（MdASMT9）的转基因苹果植株的影响。内源性 MT 通过提高抗氧化酶活性和清除活性氧（ROS）来保护转基因植物免受热胁迫，从而保护叶绿体免受损伤。施用 MT 和过表达 MdASMT9 还通过促进 MdWRKY33 介导的 MdNCED1 和 MdNCED3 的转录抑制，减少脱落酸的积累，从而诱导气孔张开以更好地散热。此外，MT 通过促进 MdWRKY33 介导的 MdATG18a 的转录增强来增强热胁迫下的自噬活性。这些发现为内源性 MT 的调节及其在提高多年生果树基础耐热性中的作用提供了新的见解。
