Drought stress negatively affects crop performance and weakens global food security. It triggers the activation of downstream pathways, mainly through phytohormones homeostasis and their signaling networks, which further initiate the biosynthesis of secondary metabolites (SMs). Roots sense drought stress, the signal travels to the above-ground tissues to induce systemic phytohormones signaling. The systemic signals further trigger the biosynthesis of SMs and stomatal closure to prevent water loss. SMs primarily scavenge reactive oxygen species (ROS) to protect plants from lipid peroxidation and also perform additional defense-related functions. Moreover, drought-induced volatile SMs can alert the plant tissues to perform drought stress mitigating functions in plants. Other phytohormone-induced stress responses include cell wall and cuticle thickening, root and leaf morphology alteration, and anatomical changes of roots, stems, and leaves, which in turn minimize the oxidative stress, water loss, and other adverse effects of drought. Exogenous applications of phytohormones and genetic engineering of phytohormones signaling and biosynthesis pathways mitigate the drought stress effects. Direct modulation of the SMs biosynthetic pathway genes or indirect via phytohormones' regulation provide drought tolerance. Thus, phytohormones and SMs play key roles in plant development under the drought stress environment in crop plants.

中文翻译：

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植物激素和次生代谢物在作物耐旱性中的相互作用：综述

干旱压力对作物性能产生负面影响并削弱全球粮食安全。它主要通过植物激素稳态及其信号网络触发下游途径的激活，从而进一步启动次生代谢物 (SMs) 的生物合成。根感知干旱胁迫，信号传播到地上组织以诱导系统性植物激素信号传导。全身信号进一步触发 SM 的生物合成和气孔关闭以防止水分流失。SM 主要清除活性氧 (ROS) 以保护植物免受脂质过氧化，并执行额外的防御相关功能。此外，干旱诱导的挥发性 SM 可以提醒植物组织在植物中发挥缓解干旱胁迫的功能。其他植物激素诱导的应激反应包括细胞壁和角质层增厚、根和叶形态改变以及根、茎和叶的解剖结构变化，从而最大限度地减少氧化应激、水分流失和干旱的其他不利影响。植物激素的外源应用和植物激素信号传导和生物合成途径的基因工程减轻了干旱胁迫效应。SMs 生物合成途径基因的直接调节或通过植物激素的调节间接调节提供了耐旱性。因此，植物激素和SMs在作物植物干旱胁迫环境下的植物发育中起着关键作用。植物激素的外源应用和植物激素信号传导和生物合成途径的基因工程减轻了干旱胁迫效应。SMs 生物合成途径基因的直接调节或通过植物激素的调节间接调节提供了耐旱性。因此，植物激素和SMs在作物植物干旱胁迫环境下的植物发育中起着关键作用。植物激素的外源应用和植物激素信号传导和生物合成途径的基因工程减轻了干旱胁迫效应。SMs 生物合成途径基因的直接调节或通过植物激素的调节间接调节提供了耐旱性。因此，植物激素和SMs在作物植物干旱胁迫环境下的植物发育中起着关键作用。