The Functional Change and Deletion of FLC Homologs Contribute to the Evolution of Rapid Flowering in Boechera stricta

Abstract

Differences in the timing of vegetative-to-reproductive phase transition have evolved independently and repeatedly in different plant species. Due to their specific biological functions and positions in pathways, some genes are important targets of repeated evolution – independent mutations on these genes caused the evolution of similar phenotypes in distantly related organisms. While many studies have investigated these genes, it remains unclear how gene duplications influence repeated phenotypic evolution. Here we characterized the genetic architecture underlying a novel rapid-flowering phenotype in Boechera stricta and investigated the candidate genes BsFLC1 and BsFLC2. The expression patterns of BsFLC1 suggested its function in flowering time suppression, and the deletion of BsFLC1 is associated with rapid flowering and loss of vernalization requirement. In contrast, BsFLC2 did not appear to be associated with flowering and had accumulated multiple amino acid substitutions in the relatively short evolutionary timeframe after gene duplication. These non-synonymous substitutions greatly changed the physicochemical properties of the original amino acids, concentrated non-randomly near a protein-interacting domain, and had greater substitution rate than synonymous changes. Here we suggested that, after recent gene duplication of the FLC gene, the evolution of rapid phenology was made possible by the change of BsFLC2 expression pattern or protein sequences and the deletion of BsFLC1.

Evolutionary processes from the perspective of flowering time diversity

“…Consistent with these patterns, seven additional FLC alleles that have sustained independent TE insertions are associated with reduced gene expression and earlier flowering (Lempe et al , ; Quadrana et al , ). Furthermore, natural variants that eliminate, attenuate, or otherwise alter the functions of FRI , FLC , and CO homologs have been implicated in the adaptive evolution of seasonal flowering in three other species (Yang et al , ; Baduel et al , ; Lee et al , ) and between species (Kiefer et al , ) in another genus in the Brassicaceae.…”

Genetic architecture and adaptation of flowering time among environments

“…n = 401 genotypes. One early flowering mutant in Flowering Locus C (Lee et al ., 2018) is not shown.…”

Repeated rearrangement of the GSL‐AOP locus contributed to spatio‐temporal variation in defense chemistry in Arabidopsis

“…nematodes, gnats and clubroot disease [39][40][41] . Similar to the GSL-AOP locus, FLC has been a target of repeated rearrangements in A. thaliana and other Brassicaceae [42][43][44][45][46][47][48] ; and like GSL-AOP, the FLC locus showed increased genetic variation in the Caucasus region.…”