高频率使用ALS抑制剂类除草剂对固氮鱼腥藻的致毒分子机理研究

Acetolactate synthase (ALS) inhibitor herbicides capable of suppressing weeds at extremely low application rates and mammalian toxicity was viewed as an important advancement in chemical weed control. Nitrogen-fixing cyanobacteria are vital photosynthetic microorganisms that contribute to soil fertility by fixing atmospheric nitrogen, and also because they maintain ecosystem stability. However, cyanobacteria are very sensitive to these herbicides because they possess many characteristics of weeds such as photosynthesis and ALS enzyme. While ALS-inhibiting herbicides were applied in the fields to control weeds must be resulted in harm to non-target nitrogen-fixing cyanobacteria as biofertilizers. The objectives of this research were to based on the toxic effects of bensulfuron and metsulfuron to nitrogen-fixing cyanobacterium (Anabaena azotica) on: (1) cloning, express and structural and functional analysis of the ALS gene to explore its binding sites for Anabaena azotica ALS; (2) establishment of the enzyme-substrate-inhibitor role model by quantum chemical analysis to clarify the mechanism of toxicity of ALS-inhibiting herbicides on Anabaena azotica; and (3) to expound the relationship between gene mutations and resistance to culture nitrogen-fixing cyanobacteria mutant to resist to ALS -inhibiting herbicides.

乙酰乳酸合成酶（ALS）抑制剂类除草剂在防除杂草的同时，造成了对具ALS的非靶标优质资源生物- - 固氮蓝藻的危害。本研究以常用ALS抑制剂- - 苄嘧磺隆、甲磺隆为对象，在对固氮鱼腥藻(Anabaena azotica)毒性效应的研究基础上，通过对ALS基因的克隆、表达以及结构和功能分析，探索其与固氮鱼腥藻ALS的结合位点，以量子化学分析建立酶-底物-抑制剂作用模型，阐明ALS抑制剂类除草剂对固氮鱼腥藻的致毒机理，确立基因突变与抗药性之间的关系，并通过构建A. azotica ALS抗性突变体，培植固氮蓝藻的ALS抑制剂抗性藻种，为在高效绿色化学除草剂广泛应用框架下固氮蓝藻的协同发展提供科学依据，对发挥固氮蓝藻在农田固氮-固碳-减排生态体系中作用，降低农用化学品使用，保障生态环境安全具有重要意义。

通过四年来，对高频率使用 ALS 抑制剂类除草剂对固氮鱼腥藻的致毒分子机理研究，在获得常用ALS抑制剂对固氮鱼腥藻(Anabaena azotica)毒性效应的研究基础上，通过对ALS基因的克隆、表达以及结构和功能分析，探索其与固氮鱼腥藻ALS的结合位点，以量子化学分析建立酶-底物-抑制剂作用模型，阐明了ALS抑制剂类除草剂对固氮鱼腥藻的致毒机理，确立了基因突变与抗药性之间的关系，并构建了A. azotica ALS抗性突变体，并对受损细胞修复和二者协同应用进行了探索，为在高效绿色化学除草剂广泛应用框架下固氮蓝藻的协同发展提供科学依据，对发挥固氮蓝藻在农田固氮-固碳-减排生态体系中作用，降低农用化学品使用，保障生态环境安全具有重要意义。