Zhao Qiang, Shen Wanzheng, Gu Yanhua, Hu Jiachen, Ma Yue, Zhang Xinlin, Du Yanli, Zhang Yuxian, Du Jidao
Heilongjiang Bayi Agricultural University, Key Laboratory of Ministry of Agriculture and Rural Affairs of Soybean Mechanized Production, Daqing, PR China.
Research Center of Saline and Alkali Land Improvement Engineering Technology in Heilongjiang Province, Daqing, PR China.
Physiol Plant. 2023 Jul-Aug;175(4):e13983. doi: 10.1111/ppl.13983.
Saline-alkali stress (SS) is a common abiotic stress affecting crop cultivation worldwide, seriously inhibiting plant growth and biomass accumulation. Melatonin has been proven to relieve the inhibition of multiple abiotic stresses on plant growth. Therefore, soybean cultivars Heihe 49 (HH49, SS-tolerant) and Henong 95 (HN95, SS-sensitive) were pot-cultured in SS soil and then treated with 300 μM melatonin at the V1 stage, when the first trifoliate leaves were fully unfolded, to investigate if melatonin has an effect on SS. SS increased reactive oxygen species (ROS) accumulation in soybean leaves and thereby induced DNA oxidative damage. In addition, SS retarded cell growth and decreased the mesophyll cell size, chloroplast number, photosynthetic pigment content, which further reduced the light energy capture and electron transport rate in soybean leaves, and affected carbohydrate accumulation and metabolism. However, melatonin treatment reduced SS-induced ROS accumulation in the soybean leaves by increasing antioxidant content and oxidase activity. Effective removal of ROS reduced SS-induced DNA oxidative damage in the soybean leaf genome, which was represented by decreased random-amplified polymorphic DNA polymorphism, 8-hydroxy-20-deoxyguanine content, and relative density of apurinic/apyrimidinic-sites. Melatonin treatment also increased the volume of mesophyll cells, the numbers of chloroplast and starch grains, the contents of chlorophyll a and b and carotenoids in soybean seedling leaves treated with SS, thereby increasing the efficiency of effective light capture and electron transfer and improving photosynthesis. Subsequently, carbohydrate accumulation and metabolism in soybean leaves under SS were improved by melatonin treatment, which contributes to providing basic substances and energy for cell growth and metabolism, ultimately improving soybean SS tolerance.
盐碱胁迫（SS）是一种常见的非生物胁迫，影响着全球范围内的作物种植，严重抑制植物生长和生物量积累。褪黑素已被证明可缓解多种非生物胁迫对植物生长的抑制作用。因此，将大豆品种黑河49（HH49，耐盐碱）和合农95（HN95，盐碱敏感）种植于盐碱土壤中，在第一片三出复叶完全展开的V1阶段用300μM褪黑素处理，以研究褪黑素对盐碱胁迫的影响。盐碱胁迫增加了大豆叶片中活性氧（ROS）的积累，从而诱导DNA氧化损伤。此外，盐碱胁迫阻碍细胞生长，减小叶肉细胞大小、叶绿体数量和光合色素含量，进而降低大豆叶片的光能捕获和电子传递速率，并影响碳水化合物的积累和代谢。然而，褪黑素处理通过增加抗氧化剂含量和氧化酶活性，减少了盐碱胁迫诱导的大豆叶片中ROS的积累。有效清除ROS减少了盐碱胁迫诱导的大豆叶片基因组中的DNA氧化损伤，表现为随机扩增多态性DNA多态性、8-羟基-2'-脱氧鸟苷含量和无嘌呤/无嘧啶位点相对密度降低。褪黑素处理还增加了盐碱胁迫处理的大豆幼苗叶片中叶肉细胞体积、叶绿体和淀粉粒数量、叶绿素a、叶绿素b和类胡萝卜素含量，从而提高了有效光捕获和电子传递效率，改善了光合作用。随后，褪黑素处理改善了盐碱胁迫下大豆叶片中的碳水化合物积累和代谢，这有助于为细胞生长和代谢提供基本物质和能量，最终提高大豆对盐碱胁迫的耐受性。
