探索植物长期跨代效应的适应性产生机制

The transgenerational effect describes the phenomenon that the phenotypes and performance of offspring are altered by the environments experienced by or/and the behavior of parental generations. Such an effect can be adaptive, when parental generations prepare their offspring for the environment (often similar to the parental environment), and thus enhance the offspring fitness. Meanwhile, the parental environment may not only have significant effects on their sons/daughters, but may have long-term effects on the later generations (grand-sons/daughters). Especially, effects underlined by epigenetic mechanisms are expected to be transmitted to even further generations of offspring. Exploring the patterns and mechanisms of long-term adaptive transgenerational effect, can not only provide additional explanations for the rapid adaptation to changing environments (associated with climate change or biological invasions), but also supplement our understanding of non-mendelian inheritance and current adaptive evolution theory. In this study, we will choose the model plant species, Arabidopsis thaliana, as the study material, which has a short life-cycle, and a small and well-noted genome. We plan 1) to investigate the patterns of long-term transgenerational effects, through tracking the phenotypic changes across multiple offspring generations in a common environment, 2) to analyze the adaptiveness of these effects, through conducting reciprocal transplanting experiment, and 3) to find corresponding epigenetic changes for these effect, through revealing whole-genome single methylation polymorphism (SMP) on offspring. This study, hopefully, will offer the first piece of evidence of long-term transgenerational effect on offspring generations later than F3. Meanwhile, as a first attempt of using whole-genome epignotyping technique for exploring mechanisms underlining long-term adaptive transgenerational effect, this study will also serve as preliminary research work for further understanding the direction and stability of epigenetic changes.

跨代效应是指亲代的行为或环境影响子代的表现和性状的现象。效应具有潜在的适应性，即亲代可以为子代做准备，提高子代的适合度。跨代效应也不局限在亲子之间，特别是由表观遗传机制引起的效应，可以表现在子二、三代，甚至可能延续至后续子代。对长期效应的适应性机制的探索，将会帮助我们了解生物对（如全球变化、生物入侵引起等的）变化环境的快速适应过程，也会丰富我们对非孟德尔遗传和适应性进化的认识。本项目将选用世代周期短、基因组已知的模式植物拟南芥为研究材料：1）在同质环境中，追踪（亲代来自不同环境的）多个子世代的表型变化，了解效应的长期性；2）开展交互移栽实验，分析效应的适应性；3）表征子代全基因组单位点甲基化，寻找和效应相关的表观变异位点。本项目是首次将跨代效应的探索延续至子四代，也是首次用全基因组的表征手段分析跨代效应的适应性机制，希望本研究可以为揭示表观遗传变异的方向和稳定性奠定科学基础。

传代效应是亲代经历的环境对子代的影响，这一效应可以使得子代受益，因此具有适应意义。本项目通过Meta-analysis研究揭示了动植物中传代效应具有普遍的适应意义，这一研究还表明传代效应可惠及三代子孙。为了实验研究传代效应的持续性，本项目选用模式植物拟南芥搭建了多世代传代效应研究实验体系，表型测量的结果证实了传代效应可以影响多个子代，更重要的是传代效应的大小与遗传相关，可能是自然选择的结果。为了深入挖掘传代效应的分子机制，本项目还发展了一套高灵敏度的全基因组甲基化分析手段，可以大幅度的提高数据的利用率和可检测位点的比率，为今后传代效应的分子机制的探索奠定基础。本项目突破传统的理论体系，通过大数据分析和实验研究将传代效应的适应性从个案拓展为普遍情形。因此，传代效应是应对环境变化的重要适应性策略，未来的研究需结合多组学分析深入理解传代效应的机制。