中华猕猴桃复合体及其近缘种的分子谱系地理学研究

The global climate changes have brought serious challenge to biodiversity conservation, but the pattern of adaptive evolution for the most plant species are poorly understood, which is very important for the effective conservation of plants in the long term. As a young and fast-growing field, molecular phylogeography has been used to analyses the geographical distribution of genealogical lineages. It resolves questions about the formation process and historical causes of the spatiotemporal pattern in genetic variation of species with the geographical environment and historic changes of global climates. Then we have the opportunity to understand the mechanism of species migration, the process of differentiation or evolution by the geographic isolation and the rule of the adaptive evolution. Actinidia chinensis complex and its closely related species, an important economic plant group endemic in China, are collected as experimental materials in the project. The geographical pattern of genetic variation and phylogeography will be study using molecular markers or sequences in both nuclear and cytoplasmic genome. Meanwhile, the geographic pattern of ploidy variation will be analyzed using the Flow Cytomely Method. The mechanism of species migration, differentiation by geographic isolation and the evolutionary process against global climate changes would be explored, which will help us to understand the historical causes of the geographic patterns of genetic variation and the rule of adaptive evolution. The results of this study will provide a scientific theoretical basis for making the long-term conservation strategies of the unique fruit and other important plant resources under the background of the global climate changes. At the same time, the results will be of great practical value for the long-term reserves and sustainable utilization of the strategy plant resources.

全球气候变化给生物多样性的保护带来了严重挑战，而绝大多数植物类群的适应性进化规律尚不清楚，给植物类群的长期有效保护带来了难题。分子谱系地理学通过研究物种遗传变异的地理分布格局，同时结合地理环境与气候变迁来探讨其遗传变异时空格局的形成过程与历史成因，从而揭示物种迁移、隔离分化与演变的过程及其适应性进化规律。本项目选择我国重要经济植物类群中华猕猴桃复合体（Actinidia chinensis complex）及近缘种作为研究对象，采用核-质分子标记或序列分析方法开展分子谱系地理学研究，并结合形态与倍性变异地理格局的分析，探讨猕猴桃植物类群应对全球气候变迁而发生的物种迁移、隔离分化与演变过程，理解其遗传变异地理格局的历史成因及其适应性进化规律，为全球气候变化背景下我国特有果树等重要战略植物资源长期保育策略的制定提供科学理论依据或基础数据，对我国战略植物资源的长期储备与可持续利用具有重要科学理论

为了揭示猕猴桃植物随全球气候变化而形成的适应性进化的规律，更好地制定其自然种质资源长期保育策略，本研究选择我国重要经济植物类群中华猕猴桃复合体（Actinidia chinensis complex）及近缘类群开展倍性变异、核-质基因组变异的谱系地理学研究，探讨地理环境、气候变迁对其遗传变异时空格局形成的影响，揭示其物种迁移、隔离分化与演变过程及其适应性进化规律。研究主要结果表明：1.中华猕猴桃原变种与美味变种分别以偏东和偏西分布，并在豫西南-鄂西北-武陵山系-雪峰山系一带形成自然重叠混合分布；近二三十年来，人为因素的影响已导致其野生分布新变化，美味变种在东部区域已出现零星野外新分布；同时由于人为破坏，自然分布的猕猴桃资源存在急剧减少的潜在威胁；2.倍性变异研究表明中华原变种主要存在二倍体、四倍体小种，而美味变种存在二倍体、四倍体和六倍体3个倍性小种，并按不同山系形成复杂错综的地理分布格局；另外还发现个别的8倍体、3倍体以及嵌合倍性等特殊倍性植株；3.cpDNA的序列分析揭示中华猕猴桃复合体存在丰富的单倍型多态性，不同单倍型的分布有着明显地理区域性，呈现地理谱系结构；4.基于核基因组SSR标记的分析表明中华猕猴桃按山系形成居群遗传结构，山系间的平原开阔地段及山脉岭脊均能产生一定的居群间基因流障碍，中华猕猴桃复合体可能存在多个冰期孑遗扩散中心，但目前相关证据较弱，有待后续研究提供更多支持依据；由于猕猴桃自然资源具有明显的山系特征，在制定其资源保护策略时应充分考虑各山脉情况制定合理的保护策略。