Data from: Adaptation to climate through flowering phenology: a case study in Medicago truncatula

Local climatic conditions likely constitute an important selective
pressure on genes underlying important fitness-related traits such as
flowering time and in many species flowering phenology and climatic
gradients strongly covary. To test whether climate shapes genetic
variation on flowering time genes and to identify candidate flowering
genes involved in the adaptation to environmental heterogeneity, we used a
large M. truncatula core collection to examine the association between
nucleotide polymorphisms at 224 candidate genes and both climate variables
and flowering phenotypes. Unlike genome-wide studies, candidate gene
approaches are expected to enrich for the number of meaningful trait
associations because they specifically target genes that are known to
affect the trait of interest. We found that flowering time mediates
adaptation to climatic conditions mainly by variation at genes located
upstream in the flowering pathways, close to the environmental stimuli.
Variables related to the annual precipitation regime reflected selective
constraints on flowering time genes better than the other variables tested
(temperature, altitude, latitude or longitude). By comparing phenotype and
climate associations, we identified 12 flowering genes as the most
promising candidates responsible for phenological adaptation to climate.
Four of these genes were located in the known flowering time QTL region on
chromosome 7. However, climate and flowering associations also highlighted
largely distinct gene sets, suggesting different genetic architectures for
adaptation to climate and flowering onset.