Data from: Independent FLC mutations as causes of flowering time variation in Arabidopsis thaliana and Capsella rubella

Capsella rubella is an inbreeding annual forb closely related to Arabidopsis thaliana, a model species widely used for studying natural variation in adaptive traits such as flowering time. Although mutations in dozens of genes can affect flowering of A. thaliana in the laboratory, only a handful of such genes vary in natural populations. Chief among these are FRIGIDA (FRI) and FLOWERING LOCUS C (FLC). Common and rare FRI mutations along with rare FLC mutations explain a large fraction of flowering-time variation in A. thaliana. Here we document flowering time under different conditions in 20 C. rubella accessions from across the species' range. Similar to A. thaliana, vernalization, long photoperiods and elevated ambient temperature generally promote flowering. In this collection of C. rubella accessions, we did not find any obvious loss-of-function FRI alleles. Using mapping-by-sequencing with two strains that have contrasting flowering behaviors, we identified a splice-site mutation in FLC as the likely cause of early flowering in accession 1408. However, other similarly early C. rubella accessions did not share this mutation. We conclude that the genetic basis of flowering-time variation in C. rubella is complex, despite this very young species having undergone an extreme genetic bottleneck when it split from C. grandiflora a few tens of thousands of years ago.

红荠（Capsella rubella）是一种自交型一年生草本植物，与广泛用于研究开花时间等适应性性状自然变异的模式物种拟南芥（Arabidopsis thaliana）亲缘关系密切。尽管实验室中数十个基因的突变均可影响拟南芥的开花进程，但在自然种群中仅少数这类基因存在序列变异。其中核心基因为FRIGIDA（FRI）与FLOWERING LOCUS C（FLC）。常见与稀有FRI突变辅以稀有FLC突变，可解释拟南芥中大部分的开花时间变异。本研究对覆盖红荠分布范围的20份红荠种质系在不同环境条件下的开花时间进行了记录。与拟南芥类似，春化作用、长光周期与升高的环境温度通常均可促进红荠开花。在本研究的红荠种质系集合中，未发现任何明确的功能丧失型FRI等位基因。通过对开花性状存在显著差异的两个株系开展测序定位，我们鉴定出FLC基因上的一处剪接位点突变，该突变可能是导致种质系1408早花的原因。但其他表型类似的早花红荠种质系并未携带该突变。尽管红荠这一物种在数万年前从大花荠（Capsella grandiflora）分化后经历了极端的遗传瓶颈，本研究仍表明红荠的开花时间变异的遗传基础极为复杂。