西藏野生拟南芥开花时间变异的遗传基础

Genetic Basis of Flowering Time Variations in Tibetan Arabidopsis thaliana

开花时间是被子植物生活史中的关键节点。十字花科植物拟南芥(Arabidopsisthaliana)广布于世界各地,在海拔4 000m以上的青藏高原也发现了该物种的自然居群,高原独特的环境塑造了其生活史的独特表型,在开花时间上表现为中等程度早花。该研究构建了西藏拟南芥Lhasa居群的F2代作图群体,基于全基因组测序的QTL-seq定位分析,在该居群中定位到主效基因FLC,并且鉴定到其第1个内含子中存在2307bp的缺失,这种单倍型只存在于西藏拟南芥居群。利用CRISPR-Cas9技术构建了Lhasa背景的flc^(-/-)突变体,表现为开花时间显著提前。研究结果表明,西藏拟南芥开花时间改变的主要原因是FLC第1个内含子缺失,该变异并未使其丧失全部功能,这可能有利于西藏拟南芥适应青藏高原独特的气候环境。

Flowering time is a critical point in the life cycle of angiosperm plants.Arabidopsis thaliana of the Brassicaceae is widely distributed around the world,and the natural populations of this species have been found at altitude 4000 m in the Qinghai-Tibet Plateau.The cold/short summer plateau climate has shaped their flowering time to be moderately early compared with those living in low altitude areas.In this study,we constructed an F2 mapping population and utilized whole-genome sequencing-based QTL-seq analysis to locate the major effect QTLs in Lhasa population of A.thaliana,and identified a haplotype-specific deletion of 2307 bp within the first intron of FLC,which is unique to Tibetan A.thaliana.Lhasa population flc^(-/-)mutant was constructed by CRISPR-Cas9 gene editing technique.The mutant exhibited significantly earlier flowering time than Lhasa.The above findings suggested that the deletion in the first intron of FLC in Tibetan A.thaliana was most likely the major cause for the early flowering phenotype,although it did not cause complete function loss of the FLC.This variation may have facilitated the adaptation of Tibetan A.thaliana to the unique climatic environment of the Qinghai-Tibet Plateau.