基于RAD-seq的特有植物灵宝杜鹃繁殖生物学及保护遗传学研究

There are abundant rhododendron germplasm resources in China. However, some unattended wild species with small populations have been extinct or are on the verge of extinction due to the narrow habitats and severe anthropogenic interference. Rhododendron henanense subsp. lingbaoense (Ericaceae, Rhododendron) is a rare and endemic species in Henan Province. Because of its narrow distribution and poor natural regeneration capability, the population size has been shrinking, and systematic research and protection has become increasingly urgent. This project is based on the field investigation of R. henanense subsp. lingbaoense, combined with the observation of flower characteristics, artificial pollination and paternal analysis to study its breeding system. Combining research on flowering phenology, pollination mechanism and seed physiology and ecology, the reproductive and survival ability of R. henanense subsp. lingbaoense wild populations were comprehensively analyzed, and the endangered reasons were revealed. Simplified genomic sequencing and SNPs locus analysis of representative individuals of all populations were conducted based on RAD-seq technique. The genetic indices of existing populations are estimated, and the genetic relationship among populations are analyzed to provide important information for the conservation strategy. The study will provide scientific basis for the effective protection and sustainable use of R. henanense subsp. lingbaoense germplasm resources. It also provides reference for the protection of other endemic wild germplasm resources.

我国具有丰富的杜鹃种质资源，但随着社会经济活动加剧，一些居群小且未受关注的野生种，由于生境狭窄、人为干扰，已经灭绝或濒临灭绝。灵宝杜鹃隶属杜鹃花科杜鹃属，是河南特有物种，因分布范围狭窄、自然更新能力差等原因，种群规模日益缩小，对其进行系统研究与保护已日益迫切。本项目以灵宝杜鹃野外调查为基础，结合花部特征观测、人工传粉、父本分析等技术，研究其繁育系统；综合开花物候、传粉机制、种子生理生态研究，分析其野生居群的繁殖能力及存活力。基于RAD-seq（Restriction-site Associated DNA sequencing）技术，对所有居群的代表性个体进行简化基因组测序和SNPS位点分析，从分子水平估算现有居群的群体遗传性指标，分析不同居群间的遗传关系，为保护策略的制定提供重要信息。研究结果可为灵宝杜鹃的有效保护与可持续利用提供科学依据，并对其他地方特有野生种质资源的保护提供参考。

灵宝杜鹃为杜鹃花科杜鹃花属的河南特有植物，因分布范围狭窄、自然更新能力差等原因，种群规模日益缩小，对其进行系统研究与保护已日益迫切。花部特征观测及父本分析实验表明，灵宝杜鹃属于兼性或专性异交的繁育系统；种子萌发实验与种群高水平遗传多样性表明，其种子特征和种群遗传特性不是其濒危的主要原因；育苗实验表明凋落物等立地条件对灵宝杜鹃种子出苗率影响明显。基因组重测序与群体遗传分析显示，灵宝杜鹃种群都保持着高水平的遗传多样性，其现存的四个种群可能起源于同一个祖先种群。由于灵宝杜鹃生境受到历史上长期采矿活动和人为干扰，项目组在野外考察时发现灵宝杜鹃野生种群中很少有幼苗和小树，因此，需要着重加强恢复和保护其自然栖息地。同时，由于立地条件影响种群的自然更新，建议在就地保护过程中进行适当的人为干扰促进种群自然更新。此外，种群历史动态分析显示，灵宝杜鹃的种群数量伴随着更新世的气候震荡而呈长期下降趋势。因此，建议采集不同种源的种子进行种质资源保存及幼苗繁育，并在此基础上开展种群恢复与回归自然的实验研究及保护实践工作。