干旱是农业生产中存在的严重问题，探明植物抗旱机理，将为农业增产增收提供重要保障。已有研究表明，植物适应胁迫能力的提高与激素诱导的抗氧化防护有关。然而，关于干旱胁迫下生长素（IAA）所诱导的抗氧化防护及信号转导机制的研究较少。本项目以耐旱型大豆品种‘科丰1号’为材料，采用水培试验，对干旱胁迫下钙离子/钙调素信号系统（Ca2+/CaM）是否参与IAA诱导大豆叶片抗氧化酶以及过氧化氢（H2O2）与Ca2+/CaM之间的关系进行研究。具体内容包括：干旱胁迫下Ca2+/CaM在IAA诱导大豆叶片各细胞分区抗氧化酶中的作用；干旱胁迫积累的IAA对大豆叶片抗氧化酶mRNA和蛋白表达量的影响；干旱胁迫下在IAA诱导大豆叶片抗氧化酶mRNA和蛋白表达中H2O2与Ca2+/CaM的关系。本项目旨在加深人们对干旱胁迫下IAA信号转导作用的理解，为干旱地区作物栽培的激素调控、干旱条件下大豆的化学调控提供理论依据。

Drought is a serious problem existed in agricultural production. Study of the mechanism of plant drought resistance will provide an important safeguard for the increase of agricultural production and incomes. Previous studies have shown that the enhanced adaptive ability of plant to stresses was related to phytohormone-induced expression of antioxidant genes and phytohormone-enhanced capacity of antioxidant defense systems. However, it is little work for the roles and signaling of indole-3-acetic acid (IAA) in drought-induced antioxidant defense. Kefeng 1, a soybean (Glycine max [L.] Merr.) cultivar, shows strong resistance to drought stress. A hydroponic experiment is conducted using Kefeng 1 to investigate whether Ca2+/CaM involves IAA-induced antioxidant defense of leaves and what relationship there is between Ca2+/CaM and H2O2 in IAA signaling under drought stress. The main content includes three parts as follows: 1) The roles of Ca2+/CaM in the H2O2-induced antioxidant defense in different subcellular compartments in soybean leaves under drought stress. 2) Effects of drought stress-induced IAA accumulation on mRNA and protein expressions of antioxidant enzymes. 3) The relationship between Ca2+/CaM and H2O2 in IAA-induced mRNA and protein expressions of antioxidant enzymes in soybean leaves exposed to drought stress. Based on this study we may further understand the roles and signaling of IAA in plants in response to drought stress, and provide a theoretical basis for the regulation of plant hormone in the production and cultivation of crop in arid regions.