侧根的发生可以增强植物根系对水分和矿质营养的吸收能力，在受到干旱胁迫时首先做出反应。褪黑素（Melatonin）是一种天然抗氧化剂，不仅促进植物体根系的建成还能增强其对逆境胁迫的抵御能力，然而关于干旱胁迫下外源褪黑素对春大豆侧根发育及调控根系发育的内在机理所知甚少。本项目利用旱棚盆栽和室内籽粒萌发试验系统，采用干旱敏感和不敏感型大豆品种，设置干旱胁迫处理，并结合幼苗表型指标测定、内源激素的变化、抗氧化酶活性分析、RNA-Seq高通量测序等关键技术和手段，明确褪黑素对干旱胁迫下大豆侧根相关生理指标的变化规律，解析籽粒萌发和幼苗生长感知干旱信号后测根的促生机理，并最终揭示外源褪黑素促进大豆苗期侧根发育的内在机制。本研究在理论上有助于深入理解外源褪黑素提高大豆干旱抗性机制，在实践上为褪黑素应用提供科学依据。

The growth of lateral roots can enhance the absorption ability of plant roots to water and mineral nutrients with reacting first to drought stress. Melatonin is a natural antioxidant that not only promotes the growth of plant roots but also improves plant resistance to adversity stress. However, little is known about the mechanism of exogenous melatonin on the promoting of drought stress with lateral root initiation and regulation of root system development at spring soybean seeding. In order to clarify the mechanism of exogenous melatonin on the promoting of drought stress with lateral root initiation, experiments will be carried out using pot experiment in dry shed and seed germination test system in laboratory with drought sensitive and insensitive soybean varieties, drought stress treatments will be set up. The main techniques used include seedling phenotypic indexes, endogenous hormones, antioxidant enzymes activities, RNA-Seq high-throughput sequencing analysis. Base on the results, we can identify the regulation of relative physiological indexes under drought stress, analyze the mechanism of melatonin in promoting the growth of lateral root growth with seed germination and early seedling growth under drought stress. At the end reveal the mechanisms of exogenous melatonin on the promoting of drought stress with lateral root initiation. This study can help understanding the mechanism of exogenous melatonin improve soybean resistance to drought stress and provide scientific bases for the application of melatonin in practice.