Joint FAFU-Dalhousie Lab, College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
College of Horticulture, Northwest Agriculture and Forestry University, Yangling, 712100, China; Joint FAFU-Dalhousie Lab, College of Horticulture, Fujian Agriculture and Forestry University, Fuzhou, 350002, China.
Ecotoxicol Environ Saf. 2020 Sep 1;200:110779. doi: 10.1016/j.ecoenv.2020.110779. Epub 2020 May 24.
Melon is of great value in food, medicine and industry. In recent years, the continuous cropping obstacles of melon is increasingly prominent, which seriously affects the cultivation. Autotoxicity is the key factor for the obstacles. Root is the first line against autotoxicity and main organs for autotoxins secretion. Some physiological responses and differentially expressed genes (DEGs) related to autotoxicity are only limited to root system. Considering the lack of relevant research, physiological researches combined with transcriptome sequencing of melon seedling after autotoxicity stress mediated by root exudates (RE) was performed to help characterize the response mechanism to autotoxicity in melon roots. The results showed that autotoxicity inhibited root morphogenesis of melon seedlings, induced the excessive accumulation of reactive oxygen species (ROS) and lipid peroxidation in roots, and activated most antioxidant enzymes. Compared with the control group, the osmoregulation substance content was always at a high level. DEGs response to autotoxicity in roots were distinguished from that in leaves. Functional annotation of these DEGs suggested that autotoxicity affected biological regulation in a negative manner. DEGs were mainly involved in the synthesis of antioxidants, DNA damage and metabolism, and stress response. These setbacks were associated with the deterioration of root morphogenesis, generation of dwarf and slender roots, and ultimately leading to plant death. The results may provide important information for revealing the response mechanism of root to autotoxicity, and provide theoretical basis for solving the continuous cropping obstacles in melon.
甜瓜在食品、医药和工业中具有重要价值。近年来，甜瓜连作障碍日益突出，严重影响了种植。自毒作用是障碍的关键因素。根是抵御自毒作用的第一道防线，也是自毒物质分泌的主要器官。一些与自毒作用相关的生理反应和差异表达基因（DEGs）仅局限于根系。考虑到相关研究的缺乏，本研究通过根分泌物（RE）介导的甜瓜幼苗自毒胁迫下的生理研究和转录组测序相结合，以帮助表征甜瓜根系对自毒作用的响应机制。结果表明，自毒作用抑制了甜瓜幼苗根系的形态发生，诱导根系中活性氧（ROS）和脂质过氧化的过度积累，并激活了大多数抗氧化酶。与对照组相比，渗透调节物质的含量始终处于高水平。根系对自毒作用的 DEGs 反应与叶片不同。这些 DEGs 的功能注释表明，自毒作用以负面方式影响生物调节。DEGs 主要参与抗氧化剂、DNA 损伤和代谢以及应激反应的合成。这些挫折与根形态发生的恶化、矮化和细长根的产生有关，最终导致植物死亡。研究结果可能为揭示根系对自毒作用的响应机制提供重要信息，并为解决甜瓜连作障碍提供理论依据。
