Jahan Mohammad Shah, Zhao Chang Jiang, Shi Li Bo, Liang Xiu Ren, Jabborova Dilfuza, Nasar Jamal, Zhou Xun Bo
Guangxi Key Laboratory of Agro-environment and Agro-products Safety, Key Laboratory of Crop Cultivation and Physiology, College of Agriculture, Guangxi University, Guangxi, Nanning, China.
Department of Horticulture, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Dhaka, Bangladesh.
Front Plant Sci. 2023 May 27;14:1193666. doi: 10.3389/fpls.2023.1193666. eCollection 2023.
Drought is one of the most significant abiotic stress threatening to crop production worldwide. Soybean is a major legume crop with immense economic significance, but its production is highly dependent on optimum rainfall or abundant irrigation. As the global climate changes, it is more important to find solutions to make plants more resilient to drought. The prime aimed of the study is to investigate the effect of melatonin on drought tolerance in soybean and its potential mechanisms. Soybean seedlings were treated with 20% polyethylene glycol 6000 (PEG 6000) and subjected to osmotic stress (14 days) with or without 100 μM melatonin treatment. Our results revealed that melatonin supplementation significantly mitigated PEG-induced growth retardation and increased water absorption ability. Foliar application of melatonin also increased gas exchange and the chlorophyll fluorescence attributes by the mitigation of the osmotic-induced reduction of the reaction activity of photosystems I and II, net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), electron transport activity, and photosynthetic efficiency. In addition, PEG-induced elevated production of reactive oxygen species (ROS) and malondialdehyde (MDA) content were significantly reversed by melatonin treatment. Equally important, melatonin boosted the antioxidant activities of soybean plants. Moreover, osmotic stress substantially increased abscisic acid (ABA) accumulation in roots and leaves, while melatonin-received plant leaves accumulated less ABA but roots content higher ABA. Similarly, melatonin significantly suppressed ABA biosynthesis and signaling gene expression in soybean exposed to drought stress. Furthermore, osmotic stress significantly suppressed plasmalemma () and tonoplast aquaporin () genes expression, and their transcript abundance was up-regulated by melatonin co-addition. Taken together, our results indicated that melatonin potentially improves drought tolerance of soybean through the regulation of ABA and aquaporin gene expression, increasing photosynthetic efficiency as well as enhancing water uptake efficiency.
干旱是威胁全球作物生产的最严重非生物胁迫之一。大豆是一种具有巨大经济意义的主要豆类作物，但其生产高度依赖于最佳降雨量或充足灌溉。随着全球气候变化，找到使植物更能抵御干旱的解决方案变得更加重要。本研究的主要目的是研究褪黑素对大豆耐旱性的影响及其潜在机制。用20%聚乙二醇6000（PEG 6000）处理大豆幼苗，并在有或没有100μM褪黑素处理的情况下使其遭受渗透胁迫（14天）。我们的结果表明，补充褪黑素显著减轻了PEG诱导的生长迟缓并提高了吸水能力。叶面喷施褪黑素还通过减轻渗透诱导的光系统I和II反应活性、净光合速率（Pn）、气孔导度（Gs）、蒸腾速率（Tr）、电子传递活性和光合效率的降低，增加了气体交换和叶绿素荧光特性。此外，褪黑素处理显著逆转了PEG诱导的活性氧（ROS）产量升高和丙二醛（MDA）含量增加。同样重要的是，褪黑素增强了大豆植株的抗氧化活性。此外，渗透胁迫显著增加了根和叶中脱落酸（ABA）的积累，而接受褪黑素处理的植株叶片积累的ABA较少，但根中ABA含量较高。同样，褪黑素显著抑制了干旱胁迫下大豆中ABA生物合成和信号基因的表达。此外，渗透胁迫显著抑制了质膜（）和液泡膜水通道蛋白（）基因的表达，而褪黑素共同添加上调了它们的转录丰度。综上所述，我们的结果表明，褪黑素可能通过调节ABA和水通道蛋白基因表达、提高光合效率以及增强水分吸收效率来提高大豆的耐旱性。
