Although exogenous melatonin can enhance the drought tolerance of plants, reports on the role of melatonin in drought tolerance in male reproductive organs are limited. To explore this, a pot experiment was conducted with cotton cultivar Yuzaomian 9110 to study the effects of exogenous melatonin (100, 200, and 1000 μM) on male fertility and related carbohydrate metabolism in anther under drought. Results showed that drought inhibited the translocation of carbon assimilates to anthers, however, melatonin application (100 and 200 μM) significantly improved the translocation of carbon assimilates to drought-stressed anthers. Drought reduced the deposition of starch, the hydrolysis of sucrose into hexoses, the generation of adenosine triphosphate (ATP) in anthers, restricting pollen viability and germination. Nevertheless, the appropriate melatonin concentrations (100 and 200 μM) increased the starch accumulation by enhancing ADP-glucose pyrophosphorylase and soluble starch synthases activities and accelerated the hydrolysis of sucrose by increasing sucrose synthase, acid and alkaline invertases activities in drought-stressed anthers. Appropriate melatonin concentrations (100 and 200 μM) also could help to generate more ATP for reproductive activities of drought-stressed anthers, finally increasing the pollen viability and germination of drought-stressed plants. These findings suggest that drought inhibited male fertility of cotton, but a precise melatonin application could regulate the carbohydrate balance of drought-stressed anthers to improve male fertility. This is the first report demonstrating the important role of exogenous melatonin in improving male fertility under drought conditions by regulating the carbohydrate metabolism in the male part of cotton.

中文翻译：

---

外源性褪黑素通过调节雄性组织中的碳水化合物代谢来改善干旱条件下的棉花（棉（Gossypium hirsutum L.））花粉繁殖力。

尽管外源褪黑素可以增强植物的抗旱性，但有关褪黑素在雄性生殖器官中抗旱性中作用的报道却很少。为了探索这一点，对棉花品种Yuzaomian 9110进行了盆栽试验，研究了外源褪黑素（100、200和1000μM）对干旱条件下花药中雄性育性和相关碳水化合物代谢的影响。结果表明，干旱抑制了碳同化物向花药的转运，但是，褪黑素的施用（100和200μM）显着改善了碳同化物向干旱胁迫的花药的转运。干旱减少了淀粉的沉积，蔗糖水解成己糖，在花药中生成三磷酸腺苷（ATP），从而限制了花粉的生存能力和发芽率。不过，适当的褪黑激素浓度（100和200μM）通过增强ADP-葡萄糖焦磷酸化酶和可溶性淀粉合酶的活性来增加淀粉的积累，并通过增加干旱胁迫的花药中的蔗糖合酶，酸和碱性转化酶的活性来加速蔗糖的水解。适当的褪黑激素浓度（100和200μM）还可以帮助为干旱胁迫的花药的生殖活动产生更多的ATP，最终提高干旱胁迫植物的花粉活力和发芽率。这些发现表明干旱抑制了棉花的雄性育性，但是精确的褪黑激素施用可以调节干旱胁迫的花药的碳水化合物平衡，从而改善雄性育性。