The genetic architecture of flowering in the Arabidopsis accession colonising southern Patagonia

Abstract

Flowering is a critical developmental step impacting the survival of plant species, and a plethora of complex interdependent regulatory pathways have evolved to sense and integrate environmental with endogenous signals. Extensive explorations in Arabidopsis thaliana revealed some key genes controlling flowering time and associated phenotypic traits. However, quantitative and population genetics suggest that other less explored flowering players may also have relevant impact on the natural variability, explaining adaptive developmental responses to local environments. Here, we report on the flowering time genetic architecture in A. thaliana, using a Recombinant-Inbred-Line (RIL) population constructed with accessions bearing contrasting flowering phenotypes, such as the laboratory standard Col-0 and the anthropically introduced southern Patagonia accession (Pat). Informative Quantitative-Trait-Loci (QTLs) mapping resulted in the recognition of a most significant QTL under vernalisation, localised at the end of chromosome V, and independently confirmed genetically by Heterogeneous-Inbred-Family lines (HIFs) and Near-Isogenic-Lines (NILs). Importantly, classical genes controlling flowering time and vernalisation, such as FLOWERING LOCUS T (FT), FLOWERING LOCUS C (FLC) and FRIGIDA (FRI) do not occur in this QTL. Furthermore, the associated Col-0 allele contributed to delayed flowering with an increased number of leaves and correlated increase in leaf length; however, this was counterintuitive, as Col-0 presented the contrary phenotypes when compared to Pat. We conclude that vernalisation contributing to local adaptation may be more diversely influenced across natural species variants than previously thought, with causative alleles having both positive and negative effects depending on genetic background.