基于群体转录组研究南荻早期适应的分子机制

Genetic diversity determines the potential of adaptation, but the role that gene expression diversity plays in adaptation remains poorly known. As one of the most potential energy crops in China, Miscanthus lutarioriparius needs to adapt quickly to several marginal lands. To address the adaptive potential of M. lutarioriparius in stressful environments, previously we sequenced and compared population transcriptomes of 3 sites, including a native site and two transplanted sites, and found that the genetic diversity of genes responding to stress environment decreased and the expression diversity of them increased. Previous studies suggested that the increased expression diversity played a positive role in adaptive potential of M. lutarioriparius at the early stage of adaptation. In the current proposal, we plan to choose a drier and colder site for sampling M. lutarioriparius population for RNA-seq. With the comprehensive application of bioinformatics, genetics and biostatistics, the gene expression diversity and genetic diversity will be compared across the 4 environments, and the genes with the common variation pattern will be identified as candidate adaptive genes. The correlation of the expression diversity and the extent of stress will also be analyzed. In addition, the enriched functions of those candidate adaptive genes and the expression pathway will be further analyzed. This project is to reveal the mechanism of early stage adaptation of M. lutarioriparius and to speed up the domestication of this energy crop in the marginal lands.

基因的遗传多样性决定生物适应性潜力，但基因表达多样性对适应性潜力的作用还知之甚少。南荻作为最有潜力的新一代能源作物，需要快速适应多种边际性环境。为了研究南荻的适应性潜力，本研究组前期比较了原生境和两个不同引种环境的南荻群体转录组，发现在新环境下，与逆境相关的基因的遗传多样性下降而表达多样性上升。前期研究表明基因表达多样性的升高对于南荻早期的适应性起到了积极的作用。本申请计划在前期基础上，选取更加干旱和低温的甘肃环县实验地，对该地的南荻群体进行RNA-seq。综合运用生物信息学，遗传学以及生物统计学的手段比较4种环境下的基因表达多样性和遗传多样性，通过环境间共同的变异规律鉴定适应性候选基因。并分析这些候选基因的表达多样性和遗传多样性的变化程度与外界逆境程度的相关性，以及适应性关键基因所富集的功能和表达调控路径及其相互关系等。该项目旨在揭示南荻的早期快速适应机制，加速能源作物在边际性土地驯化。

南荻作为最有潜力的新一代能源作物，需要快速适应多种边际性环境。为了研究南荻的适应性潜力，本项目在前期基础上，综合运用生物信息学，遗传学、进化生物学以及生物统计学手段，比较不同环境下基因的表达多样性和遗传多样性，通过环境间共同的变异规律鉴定适应性候选基因，分析适应性关键基因所富集的功能和表达调控路径及其相互作用关系。本研究主要取得了以下三个重要进展：1）南荻居群间存在频繁的基因流，而表达水平、遗传多样性、单倍型、群体结构和环境是决定基因表达变异的重要因素，均在不同程度上影响基因表达变异，其中环境贡献最大；2）在南荻适应环境变化的过程中，长非编码RNA比蛋白编码信使RNA对环境改变更加敏感，可能经历了更多松弛选择或者趋异进化，且长非编码RNA有助于提高水分利用效率等适应胁迫环境的重要性状；3）在新的胁迫环境中，增加的表达多样性可以补偿遗传多样性丧失导致的适应性潜力下降，使得种群保持一定水平的表型变异，以应环境快速变化。这一表达多样性增加缓冲适应性潜力快速减少的假说，通过唯象方程理论化并获得南荻群体转录组数据的支持。这些研究初步揭示南荻在早期快速适应胁迫环境的分子机制，帮助加速能源作物在边际土地的驯化。