喀斯特特有植物叶片功能性状的QTL及其与环境互作分析

Plant functional traits are the morphological and physiological features that represent adaptive strategies and determine how plants respond to environmental factors. Plant functional traits in nature are complex traits that are influenced by the genetic composition and the environment, and their interactions. Understanding the genetic basis of variation of complex traits is a frontier research field in current biology. Due to its high edaphic and topographic heterogeneity, karst region in China is characterized by high species richness and endemism and has been recognized as one of the plant biodiversity hotspots in the world. Studies of the adaptive mechanisms of plants response to karst environment is vitally important for understanging the origin and evolution of the biodiversity in this region. Quantitative trait loci (QTLs) mapping has become one of the most powerful tools in untangling genetic basis of complex traits. Our previous studies revealed great divergence in a suite of functional traits within and between Primulina species in the karst environment. In the project, we use SNP-based QTL analysis to understand the genetic architecture of several leaf function traits in two closely sympatric Primulina species (P. eburnea and P. mabaensis). We first construct a high-density linkage genetic map with an F2 population, and then we conduct QTL analysis for a suite of leaf functional traits including specific leaf area (SLA), δ13 C, leaf chlorophyll and element contents under both greenhouse and filed conditions. The goal of this study is to determine the number, location and effect of the QTLs and their interaction with environment underlying variation of leaf functional trait. Such information is critically important for understanding the ecological and evolutionary adaption of Primulina species in karst environment.

植物在长期的演化过程中，与环境相互作用，逐渐形成了许多内在生理和外在形态方面的适应性对策，即功能性状。植物功能性状本质上是由多基因和非遗传因素共同作用的复杂性状，解析复杂性状的遗传基础是现代生物学研究的一个前沿领域。喀斯特地区是我国植物多样性和特有性的关键区域，理解植物对喀斯特环境的适应机制对探讨喀斯特特有植物多样性形成与维持机制及其生物多样性保护具有重要意义。本研究以报春苣苔属同域分布的近缘物种牛耳朵（Primulina eburnea）和马坝报春苣苔(P. mabaensis)为研究材料，以SNP分子标记构建高密度遗传连锁图谱，开展不同环境条件下叶片比叶面积、δ13 C、叶绿素、叶片元素等指标的QTL定位，阐明控制叶片主要功能性状的基因组区域的数目、位置和效应；揭示报春苣苔属植物对喀斯特环境适应的遗传基础及其与环境条件的互作关系，为理解植物对喀斯特环境响应与适应的分子机制奠定基础。

报春苣苔属（Primulina）是我国华南喀斯特和丹霞地貌特殊土壤生境的典型代表类群，具有多样的微生境适应性，但针对其适应微生境的遗传机制研究甚少。短序报春苣苔（Primulina depressa）和丹霞报春苣苔（P. danxiaensis）是一对同域分布的近缘种，但是它们对微生境的适应性有显著差异，并且它们的花和叶片性状都发生了巨大的分化，此外它们的杂交后代出现雄性育性下降，因此它们是报春苣苔属植物适应性分化遗传基础研究的理想系统。本项目通过对短序报春苣苔和丹霞报春苣苔进行人工杂交，并对得到的F1进行自交，得到了包含201个个体的F2群体；并采用RAD-seq得到的分子标记构建了报春苣苔属第一幅高密度连锁图谱；对作图群体12个叶片和花性状和杂种花粉育性进行测量，并对其进行相关性分析和主成分分析（PCA）和QTL定位。性状间的相关性分析和PCA分析结果显示，12个适应性性状可以被分成3个性状组，分别是花形态性状，叶片生理性状和叶片形态性状。在此基础上对每个独立性状和被提取出的主成分（PC）进行QTL定位，我们发现同一性状组内性状的QTL位点高度交叠；同时，PC的QTL位点相互之间没有交叠，但PC的QTL位点与其对应的性状组的独立性状QTL位点高度交叠。花部性状受大量微效QTL位点控制，而叶片生理和形态性状则受到一些较大效应的位点控制。QTLST的检测结果显示，有5个花形态性状受到自然选择，而其他性状和提取的主成分没有检测到方向性选择的信号。