Key Laboratory of Horticultural Plant Genetics and Physiology, Institute of Horticulture, Jiangxi Academy of Agricultural Sciences, Nanchang, P. R. China.
Institute of Environment and Sustainable Development in Agriculture, CAAS/National Engineering Laboratory of Efficient Crop Water Use and Disaster Reduction/Key Laboratory of Agricultural Environment, Ministry of Agriculture and Rural Affairs, Beijing, P. R. China.
Plant Signal Behav. 2022 Dec 31;17(1):2086372. doi: 10.1080/15592324.2022.2086372.
Studies have not fully explained the underlying mechanism of spermidine-mediated heat tolerance. This study investigated the possible role of spermidine (Spd) in regulating citrus heat tolerance. The results showed that exogenous Spd effectively alleviated the limitation of high temperature (HT) on photosynthesis. Exogenous Spd increased the chlorophyll content, net photosynthetic rate, intercellular carbon dioxide concentration, stomatal conductance, maximum and effective quantum yield of PSII photochemistry, nonphotochemical quenching coefficient, and electron transport rate in citrus seedlings under HT stress, but declined the stomatal limitation value. In addition, Spd treatment promoted the dynamic balance of the citrus enzymatic and non-enzymatic antioxidants system. Spd application significantly increased the activity of superoxide dismutase, peroxidase, catalase, ascorbic acid, and glutathione and the expression level of corresponding genes at high temperature, while reducing the content of HO and malondialdehyde. Therefore, our findings suggested exogenous Spd significantly ameliorated citrus physiological and photosynthetic adaptation under HT stress, thereby providing helpful guidance for citrus cultivation in HT events.
研究尚未充分阐明亚精胺介导耐热性的潜在机制。本研究探讨了亚精胺（Spd）在调节柑橘耐热性中的可能作用。结果表明，外源 Spd 可有效缓解高温（HT）对光合作用的限制。外源 Spd 增加了高温胁迫下柑橘幼苗的叶绿素含量、净光合速率、胞间二氧化碳浓度、气孔导度、PSII 光化学的最大和有效量子产量、非光化学猝灭系数和电子传递速率，但降低了气孔限制值。此外，Spd 处理促进了柑橘酶和非酶抗氧化剂系统的动态平衡。Spd 处理显著提高了高温下超氧化物歧化酶、过氧化物酶、过氧化氢酶、抗坏血酸和谷胱甘肽的活性以及相应基因的表达水平，同时降低了 HO 和丙二醛的含量。因此，我们的研究结果表明，外源 Spd 可显著改善柑橘在高温胁迫下的生理和光合作用适应性，为高温事件中柑橘的栽培提供了有益的指导。
