土壤砷(As)污染主要以无机砷污染为主。好氧环境中，土壤中的无机砷主要以五价砷As(V)被水稻吸收。水稻HAC砷酸还原酶家族介导As(V)向As(III)的还原过程，是As(V)解毒的重要步骤。申请者前期研究发现，外源Fe(II)能显著提高水稻HAC砷酸还原酶基因的转录水平，促进As(V)的还原能力，但其分子机理尚不清楚。本项目拟通过观察绿色荧光蛋白(GFP)标记HAC转基因材料以及利用qRT-PCR技术，考察外源Fe(II)对HAC砷酸还原酶基因表达丰度与部位的调控作用；利用体外酶活分析以及异源表达体系，考察Fe(II)对HAC还原能力的调控作用；通过水培与盆栽实验，分析外源Fe(II)对水稻体内As(V)还原能力以及砷吸收富集能力的影响；揭示外源Fe(II)调控水稻HAC砷酸还原酶介导As(V)还原的分子机理，为调控水稻对As(V)的吸收富集，保障稻米质量安全提供理论依据。

Inorganic As soil contamination is common problem in many areas in the world. However, rice grown under upland or water-saving cultivation methods experiences long periods of aerobic soil conditions with arsenate being the predominant form of As taken up by rice. Recently, HAC arsenate reductase genes have been cloned and identified to be involved in arsenate reduction and arsenic accumulation in rice. Previous studies showed that the expression level of HAC genes and As(V) reduction ability could be improved by Fe(II). However, the mechanism of the work remains unknown. In this research, the expression level of HAC genes influenced by Fe(II) will be analyzed by the observation of GFP labeled HAC transgenic plants and qRT-PCR methods. The influence on As(V) reduction ability by Fe(II) will be identified by vitro enzyme activity analysis and heterologous expression system. Hydroponic and pot experiments with different Fe(II) conditions was conducted to investigate the phenotype and As accumulation in rice among different HAC genes transgenic plants. Results from this work will provide useful data for clarifying the molecular mechanisms of the As(V) reduction process involved by HAC arsenate reductase which was influenced by Fe(II) as well as controlling accumulation of arsenic in rice for food security.