加拿大一枝黄花多倍化增强耐热性驱动生态位分化成功入侵的机制研究

Polyploidy is believed to be one of the main driving forces of evolution for alien invasive plant. However, whether autopolyploidy is an evolutionary pathway still lacks sufficient empirical evidences. It is unknown how genome doubling caused effect by self-organization evolution plays a key role in enhancing the hot-tolerance ability for the successful invasion. It is not clarified that polyploidy enhanced invasiveness of alien plants evolves through pre-adaptation or post-introduced adaptive evolution or both joint action. Therefore, the present project will mainly focus on the above scientific issues. The native and introduced diploid, tetraploid and hexaploid Solidago canadensis populations with different dependent-ploid thermotolerance are used as materials. Polyploidy of enhanced thermotolerance accelerates the successful invasion as the starting point of this study. A comparatively systematic study is conducted on invasion biology in both native and introduced common gardens in order to elucidate the key factor of polyploidy of enhanced thermotolerance facilitating successful invasion. Related thermotolerance genes associated with systematic omics analysis reveals the key genes of increased thermotolerance. Furthermore, copies, methylation, insert site and upstream regulon of the key gene are detected and studied to illuminate molecular mechanisms of autopolyploidy of driven successful invasion. This will enrich plant invasion biology theory about the polyploidy enhancing invasiveness, and provide a theoretical basis for how to improve the thermotolerance of the crops.

多倍化是外来入侵植物演化的驱动力，但更为普遍的同源多倍化的作用仍然缺乏足够的案例证据；也不清楚基因组加倍后自组演化如何导致的耐热性效应并在增强入侵能力中扮演关键作用；其演化是预适应或后适应演化亦或两者共同作用也还存在争论。因此，本项目将围绕上述科学问题，利用原产与入侵地同源二、四、六倍体加拿大一枝黄花种群为材料，针对多倍化已经增强了其耐热能力并加速该种成功入侵的现象为切入点，在同质园条件下开展入侵生物学研究，以明确多倍化增强耐热是致拿大一枝黄花成功入侵的关键特征因子。通过耐热相关基因并结合转录组及甲基化学比较研究，揭示增强耐热性的关键基因。进一步研究耐热关键基因的拷贝数、甲基化、插入位点或上游调控因子探索多倍化引起其遗传或表观遗传变异的规律，以阐明多倍化导致其成功入侵演化的分子机制。这将丰富植物入侵生物学理论，也为如何提高作物的耐热性提供理论依据和可能利用的新遗传资源。

加拿大一枝黄花为我国一类管控的严重外来入侵物种，为了阐明其成功入侵机制，系统开展了加拿大一枝黄花全球尺度细胞地理学研究、生长繁殖、生理生化特征和同质园竞争性比较试验研究、转录组的信号通路及关键基因的温度分子适应性演化机制研究。揭示了加拿大一枝黄花倍性依赖的与纬度和气温负相关的细胞地理分布和气候生态位分化规律；阐明了多倍化在亚热带的东亚气候下通过增强耐热性、延迟开花以避热成功进行有性繁殖和无性繁殖的适应性演化机制，多倍体的耐热性主要是通过高温下较高浓度的活性氧清除酶获得的，进一步通过高温响应的HSF30、HSP22和HSP15.3基因的高表达和冷响应转录通路的SCE1多拷贝和甲基化协同温度平衡适应。验证了加拿大一枝黄花成功入侵中国是多倍化驱动的预适应和入侵后快速后适应演化的共同作用结果，且入侵后快速的后适应性演化可能是成功入侵的关键因素。总之，项目总体目标已经达成，明确了多倍化预适应和快速的后适应演化增强耐热性是加拿大一枝黄花成功入侵的关键因素，阐明了多倍化增强耐热性是关键基因拷贝数和甲基化协同调控的分子机制。培养研究生5名（其中3名已获得博士或硕士学位），在生态学领域顶级期刊Ecological Monographs等发表SCI论文8篇。获得省部级科技成果奖2项。