一氧化氮(NO)和过氧化氢(H2O2)均是普遍存在于植物体内的信号分子，二者之间互作共同参与植物生长发育的调控、对生物和非生物胁迫的感受、信号传导与适应过程。但是，关于植物镉胁迫响应过程中NO和H2O2信号传导途径及NO和H2O2间的相互关系却知之甚少，许多问题尚不清楚。本项目申请者在已明确了镉胁迫下水稻体内NO代谢特征及其作用的基础上，拟通过药理学、生理生化、细胞化学等技术，分析NO和H2O2互作对镉胁迫下水稻根尖生长、NO和H2O2含量动态变化、细胞壁组分及相关酶、抗氧化防护、MAPK活性、镉积累和耐性的影响，揭示NO和H2O2在水稻根系响应镉胁迫中的相互关系和调控水稻镉积累和耐性的机制，探明MAPK在镉胁迫响应信号转导过程中的作用及其与NO和H2O2之间的关系，旨在从信号转导方面揭示植物耐镉机制，也为今后在生产实践中应用信号物质调控植物耐镉性提供重要的理论依据和技术支持。

Nitric oxide (NO) and hydrogen peroxide (H2O2) are two kinds of unique signaling molecules in plant. The crosstalk between NO and H2O2 play key roles to modulate plant growth and development and mediate the reception, signal transduction and responses to biotic and many abiotic stresses. However, the signal transduction pathway and relationship between NO and H2O2 in plants under Cd stress are still unclear. we have investigated the resouce of NO, metabolism rule, and its relationship with Cd-tolerance for rice seedling under Cd stress. In this project, using pharmacology, plant physiology and biochemistry, cytochemistry technique, etc, the effects of crosstalk between nitric oxide and hydrogen peroxide on root tip growth, the contents of nitric oxide and hydrogen peroxide, the component of cell wall, oxidation protection, the activity of mitogen-activated protein kinases, cadmium accumulation and tolerance will be inverstigated to ellucidate the relationship, roles and mechanisms of crosstalk between nitric oxide and hydrogen peroxide in rice under cadmium stress and the role of mitogen-activated protein kinases and the relationship among nitric oxide, hydrogen peroxide and mitogen-activated protein kinases in rice root response to cadmium stress. Based on these theoretical understandings, it is very important and useful to reveal the mechanism of cadmium toxicity and tolerance from the view of signal transduction. Simultaneously, these results could provide an important technical support to improve the stress tolerance by chemical regulation in rice production.