转基因渐渗对水稻野生近缘种的进化和生态影响机制研究

The potential ecological risks caused by transgene escape from transgenic crops to wild relative species through gene flow have aroused tremendous debates over environmental biosafety issues worldwide. Previous studies indicate that transgene flow frequencies and fitness effects brought by a transgene are the keys determining the ecological consequences. Extensive studies have proven the fact of gene flow from crop to wild relatives. However, little is known about how fitness of transgene will affect the evolutionary process of wild populations, causing ecological consequences. Based on our previous work, we attempt to address the following questions by: 1) distinguishing the influences of heterosis and fertility on fitness effects in hybrid lineages derived from rice-wild relative crosses; 2) determining the fitness effects brought by insect-resistance and herbicide-resistance transgenes in hybrid lineages of rice under different selection pressure; 3) assessing the evolutionary impacts of transgressive segregates in the populations of the hybrid lineages; 4) analyzing the influences of transgenes on the segregating pattern of alleles derived from cultivated and wild rice parents in hybrid lineages; 5) modeling the long-term evolutionary effects of transgene introgression in wild rice populations based on all obtained data. Knowledge generated from this study will reveal the impacts of functional genes with a strong selective advantage on the adaptive evolution of wild relative species during the hybridization-introgression process. It will also provide important scientific bases for assessing potential ecological risks caused by transgene flow to wild relatives of rice.

转基因通过基因流逃逸到栽培植物的野生近缘种可能带来生态风险，这是全球备受争议的环境生物安全问题。导致生态风险的关键取决于基因流频率及转基因适合度效应。栽培植物基因向野生种渐渗已被大量研究证实。但转基因渐渗如何影响野生近缘种的适合度和群体进化潜力从而导致生态风险？对此却了解甚少。本项目将在前期工作基础上开展如下研究：1）分析栽培稻和野生稻近缘种杂交后代的杂种优势和育性变化对适合度的影响；2）检测抗虫和抗除草剂转基因在具有不同选择压的环境下对杂交后代的适合度效应；3）评价超亲分离后代对杂交群体进化和转基因扩散的贡献；4）分析转基因对杂种双亲基因分离和渐渗的影响；5）利用模型对已获数据进行模拟，分析转基因渐渗对野生稻近缘种群体的长期进化影响。研究结果将从理论上揭示具超强选择优势的基因在植物杂交-渐渗过程中如何影响野生近缘种的适应性进化，为转基因逃逸到野生稻近缘种及其潜在生态风险评价提供科学依据。

转基因漂移或渐渗到栽培植物的野生近缘种及其带来的潜在生态风险是全球备受争议的环境生物安全问题，对转基因漂移或渐渗如何影响野生近缘种群体进化和导致生态风险的机制进行研究非常重要。本项目以自花风媒传粉农作物水稻为模式研究材料，利用生态学、进化生物学和分子生物学研究方法，展开了转基因漂移和渐渗对水稻野生近缘种的适合度效应和生态影响机制的研究。通过项目实施，我们获得以下主要研究结果：（1）优化了转基因漂移的精准计算模型并建立了具有实用价值的转基因漂移频率预测工具；（2）检测了抗虫转基因漂移到野生稻和杂草稻的适合度效应，结果表明抗虫转基因带来的适合度影响受转基因类型、环境中的虫压（选择压）和野生近缘种遗传背景的影响，最终确认水稻抗虫转基因漂移不会带来明显的环境风险；（3）分析了抗草甘膦除草剂转基因（EPSPS）漂移到野生稻和杂草稻群体的适合度效应，结果表明即使不施用草甘膦除草剂，过量表达EPSPS的转基因漂移到野生稻和杂草稻群体均会导致一定的风险；（4）发现了转基因栽培稻与野生稻和杂草稻的杂交后代中（F2-F3），来自双亲多位点等位基因非随机分离的现象，这对于转基因漂移导致环境生物安全评价的准确性有一定影响；（5）检测了栽培稻与野生稻杂种后代中的转基因适合度和超亲分离优势的共同影响，表明EPSPS转基因渐渗对野生稻和杂草稻群体的进化潜力可能产生长期影响。上述研究结果对理解转基因渐渗水稻野生近缘种的进化和环境影响均具有重要意义，为环境安全评价和野生稻遗传资源就地保护策略制定提供科学依据。