在中国,棉花是重要的经济作物,冷胁迫对作物的发育产生负面影响,生产,和质量形成。近年来的研究表明,褪黑素(MT)可以减轻低温胁迫对植物的伤害,促进植物的生长发育。在这项研究中,研究了外源褪黑素预处理对冷胁迫下新鲁早33棉花幼苗的形态和生理变化,以研究其防御作用。结果表明,100μMMT预处理对棉花抗寒性的提高最为显著。它还改善了寒冷胁迫下棉花的枯萎状态,大大提高了光合速率(Pn),气孔导度(Gs),最大光化学效率(Fv/Fm),光合性能指数(PIabs)提高116.92%,47.16%,32.30%,和50.22%,分别,减轻了低温的不利影响。此外,补充MT使超氧阴离子(O2•-)和过氧化氢(H2O2)的积累减少了14.5%和45.49%,分别,在冷胁迫的棉花叶片中,通过调节抗氧化系统,从而减轻氧化损伤。此外,MT预处理增加了内源性褪黑素含量(23.80%)和类黄酮含量(21.44%),并显着诱导了生物合成酶相关基因的表达。以上结果表明,外源褪黑素通过调节光合性能提高棉花幼苗的耐低温性,抗氧化酶活性,抗氧化剂含量,内源性褪黑激素和类黄酮含量,以及与其合成相关的基因的表达水平。
In China, cotton is a significant cash crop, and cold stress negatively impacts the crop\'s development, production, and quality formation. Recent studies have shown that melatonin (MT) can alleviate the damage to plants under cold stress and promote good growth and development. In this study, the morphological and physiological changes induced by exogenous melatonin pretreatment on \'Xinluzao 33\' cotton seedlings under cold stress were examined to investigate its defensive effects. The results showed that 100 μM MT pretreatment improved the cold resistance of cotton most significantly. It also improved the wilting state of cotton under cold stress, greatly increased the photosynthetic rate (Pn), stomatal conductance (Gs), maximum photochemical efficiency (Fv/Fm), and photosynthetic performance index (PIabs) by 116.92%, 47.16%, 32.30%, and 50.22%, respectively, and mitigated the adverse effects of low-temperature. In addition, MT supplementation substantially reduced the accumulation of superoxide anion (O2•-) and hydrogen peroxide (H2O2) by 14.5% and 45.49%, respectively, in cold-stressed cotton leaves by modulating the antioxidant system, thereby mitigating oxidative damage. Furthermore, MT pretreatment increased the endogenous melatonin content (23.80%) and flavonoid content (21.44%) and considerably induced the expression of biosynthesis enzyme-related genes. The above results indicate that exogenous melatonin improves the low-temperature resistance of cotton seedlings by regulating photosynthetic performance, antioxidant enzyme activity, antioxidant content, endogenous melatonin and flavonoid content, and the expression levels of genes related to their synthesis.