普通野生稻边缘种群对气候变暖的适应性响应

The adaptive response of a plant to rapid climate change is a key issue in evolutionary biology and ecology. Local adaptation usually occurs in edge populations, leading them to be much vulnerable to climate change. Gene flow, one of the main driving forces of evolution, theoretically, may encounter the effects of selection that results in local adaptation, and also plays an important role on the adaptive response of edge populations to climate change. However，few of experiments were designed to examine the interaction between gene flow and local adaptation, as well as the impacts of this interaction on adaptive response to environmental changes. Wild rice Oryza rufipogon is an endangered but most agriculturally important species for rice improvement. Significant local adaption to habitat temperature was found in the northern populations of O. rufipogon. It means that climate warming is the main environmental stress that O. rufipogon has to face in the global climate change scenario. In the present project, we focus on the northern O. rufipogon populations with the relatively southern populations as controls, uses both plants from natural and artificial gene flow populations as materials to establish experiemental populations at three common gardens. According to the method of space-for-time substitution, the common gardens will be set up in the northernmost boundary, relatively northern and southern areas of the range of O rufipogon in China (i.e., high, middle and low latitude), which are the representatives of the climate temperatures of edge populations today, and that in 2065 or in more future estimated based on IPCC(2013), respectively. Combining with an experiment in greenhouse mimicking climate warming in the future, we try to investigate population performances and the variations of transcriptome and gene expression profile, to detect the adaptive response of populations to changed temperatures, to estimate the influences of gene flow on fitness and local adaptation, to reveal the molecular mechanisms underlying local adaptation and adaptive response to climate warming, to predict the potential impacts of climate change on O. rufipogon, and then to give some corresponding conservation suggestions. This project may provide important information for understanding the mechanism of plants’ response to climate change, as well as contribute to further utilization and conservation of O. rufipogon.

植物如何适应全球气候变化是当今进化生态学的核心科学问题之一。前人研究表明，本地适应性使边缘种群对气候变化十分敏感；基因流会影响选择效应，从而影响本地适应性。但基因流对本地适应性的效应及其对气候变化适应性响应的影响研究却仍然不足。普通野生稻是有关粮食安全的重要遗传资源，其北部种群对环境温度表现出明显的本地适应性，因而气候变暖是其生存面临的主要环境压力。本研究以普通野生稻北缘种群为对象，以偏南的种群为对照，以自然种群和模拟基因流的实验种群为材料，采取空间代替时间的同质园实验与模拟增温实验相结合、表型性状检测与组学分析相结合的策略，研究边缘种群对环境温度的适应性表现、基因流对适应性的影响，解析本地适应性的分子基础，阐明普通野生稻对气候变暖的响应机制，预测全球气候变化对普通野生稻的影响并提出保护建议。本研究既能促进对植物响应全球气候变化机制的认识，又可对野生稻种质资源的保护与挖掘利用提供指导。

植物如何适应全球气候变化是当今进化生态学的核心科学问题之一。本地适应性使边缘种群对气候变化十分敏感，而基因流会抵消选择效应，从而抑制本地适应性。但基因流与本地适应性的叠加效应及其对气候变化最终响应却缺乏实验研究。普通野生稻是有关粮食安全的重要遗传资源，其北部种群对环境温度表现出明显的本地适应性，因而气候变暖是其生存面临的主要环境压力。本研究以普通野生稻北缘种群DX为对象，以偏南的种群KS和HN为对照，以自然种群和模拟基因流的实验种群为材料，采取空间代替时间的同质园实验与模拟增温实验相结合、表型性状检测与组学分析相结合的策略，研究边缘种群对环境温度的适应性表现、基因流对适应性的影响。结果显示：1）普通野生稻种群的存在明显的表型可塑性与本地气候特别是温度相关的适应性；2）普通野生稻在基因组层面上发生了与地理相关的渐变变异，北缘种群拥有明显的与温度相关的适应性遗传变异；3）北缘种群DX表现出明显的本地适应性，向南或向北迁移都会使其适合度下降，暗示气候变化会影响到普通野生稻北缘种群的生存；4）中心-边缘基因流明显改变边缘种群的本地适应性，同时也促进了种群对温度变化的响应；5）组学分析结果也显示北缘种群在种子萌发阶段也存在明显的低温适应性；6）在有环境压力的情形下，补偿作用会降低基因流对普通野生稻的影响。本研究的结果既丰富人们对植物响应全球气候变化机制的认识，又对野生稻种质资源的保护与挖掘利用有指导意义。