稗草是严重影响我国水稻稳产、高产的主要恶性杂草之一,其对稻田除稗剂产生的多药抗性及其抗性种群的扩展必将威胁水稻的安全生产，尤其在大气CO2浓度不断升高的条件下，人们对稻田生态系统中多药抗性稗草种群的发展机制知之甚少。申请者拟以多药抗性稗草和敏感性稗草为研究材料，在已经获得稗草转录组测序结果的基础上，应用分子生物学、植物生理学和生态学等交叉研究手段，首先克隆稗草的C4光合关键酶基因,同时阐明CO2浓度升高条件下C4关键酶在多抗性和敏感性稗草中表达的影响差异；通过测定供试材料的光合生理指标、生物学性状指标、生育期和穗粒结构分析，阐明CO2浓度升高条件下不同品种水稻对多抗性和敏感性稗草种群的生态适合度的影响。预期研究结果将揭示C4关键酶在多药抗性稗草种群发展中的作用机理，从而解析多药抗性稗草种群适应全球气候变化的分子机制，为全球气候变化条件下保障我国粮食安全和制定农田生态安全策略提供科学依据。

Barnyardgrass (Echinochloa crus-galli) is one of the major malignant weeds which have serious impacts on the rice quantity and quality in China. The expansion of barnyardgrass resistant to multiple herbicides has become an increasing threat to rice production systems. Little is known that mechanism on multiple-herbicide resistant barnyardgrass populations in rice ecological system, especially in response to elevated atmospheric CO2 concentration([CO2]). Based on our results of screening the barnyardgrass resistant to quinclorac, bispyribac-sodium and cyhalofop-butyl group herbicides and 454 pyrosequencing results,the key enzyme genes in C4 photosynthesis will be identified using real-time PCR and the biochemical method, to study the expression of multiple-herbicide resistant barnyardgrass and susceptible barnyardgrass under elevated [CO2]. Photosynthesis parameters, biology indicators,growing stage and yield structure will be measured to elucidate the photosynthesis and ecological fitness of multiple-herbicide resistant and susceptible barnyardgrass with different varieties of rice under elevated [CO2]. Using the research tools of molecular biology, plant physiology and plant ecology, the results of this project will not only be able to uncover the mechanisms of photosynthesis enzymes affecting multiple-herbicide resistant barnyardgrass population in response to elevated [CO2], but also reveal the molecular mechanism of multiple-herbicide resistant barnyardgrass population in response to the global climate change. It will provide scientific basis for ensuring food safety and devising the tactics of ecological safety in the cropland system under the global climate change.