基于景观遗传学的方法解析连翘的适应性进化机制

The adaptive genetic mechanisms of species response to climate environment is one of the most basic problem in the field of molecular ecology and evolutionary biology. China’s warm-temperate zone is a region which has richness vegetation. However, the adaptation mechanism of species responses to environment variables in this region remains less well understood. Based on previous Forsythia suspensa phylogeographic studies, we try to disentangle the adaptive differentiation mechanism of F. suspensa in China’s warm-temperate zone using the methods of landscape genetics. In this work, SCoT and SNP markers, environmental factors, and phenotype and phenology characteristics will be used. To found genetic variation associated with environmental variables, we will identify outlier loci by genome scanning, and do the regression analysis with multiple environmental variables. To found the genetic variation and environmental factors associated with phenotype and phenology characteristics, we will also do the regression analysis between phenotype and phenology characteristics and environment associated loci, environmental factors. Furthermore, we will analyze the genetic structure, adaptive evolution of genome and phenotype and phenology characteristics, and the environmental factors associated with adaptive variation. Landscape genetics research of F. suspensa will help us to understand the species adaptation mechanism, species divergence and speciation in China’s warm-temperate zone.

生物对气候环境适应的遗传机制是分子生态学和进化生物学领域的最基本问题之一。中国暖温带是植被构成丰富的地区之一，但是我们对该区域植被物种对环境适应的机制了解甚少。本研究在前期连翘亲缘地理学研究的基础上，采用景观遗传学的方法对中国暖温带物种连翘的适应性分化机制进行解析。研究采用SCoT和SNP两种分子标记，结合环境因子，表型物候特征数据，通过鉴定选择异常的outlier位点，并将outlier位点与环境数据做关联分析，鉴定与环境变量相关的基因位点，并进一步将表型物候数据分别与环境数据、适应性基因位点做关联分析，鉴定与表型物候特征相关的环境因子及基因位点。研究通过分析连翘的空间遗传结构，基因组和表型物候特征的适应性进化，和驱动其发生适应性遗传进化的环境因子，为深入理解中国暖温带植被对环境的适应机制、物种分化和形成机制等理论研究提供科学基础。

生物对气候环境适应的遗传机制是分子生态学和进化生物学领域的最基本问题之一。本项目对连翘进行了基因组测序，获得了高质量的连翘基因组737.5 Mb，基因组的contig N50 值为7.3 Mb。我们在连翘的分布区选取了15 个连翘的自然种群，运用简化基因组SLAF对300个样本进行了基因分型。研究发现连翘的自然种群共聚类为5个遗传群体，RDA分析以及排除Outlier位点后的遗传结构对比分析发现环境变量引起的自然选择对连翘的遗传分化有显著影响，这些环境变量为果实发育期的太阳辐射、寒冷和干旱。研究在连翘基因组发现了与太阳辐射、温度、降雨相关的本地适应分化基因。在同质园实验中，正常的生长条件下连翘种群没有出现表型的显著分化。但在同等强度的干旱与胁迫条件下，连翘种群在耐寒力和耐旱力方面表现出了明显差异。连翘不同种群在同等强度的干旱胁迫下与类黄酮和芳香物质相关基因发生了表达分化，在同等强度的寒冷胁迫下与脂质氧化、异喹啉生物碱、半乳糖、酪氨酸、不饱和脂肪酸相关的基因发生了表达分化。本项目为理解植物在环境梯度下的本地适应的遗传基础提供了科学基础。