Flowering Times of Wild Accessions From Across Norway Correlate With Expression Levels of , , and Genes.

Temperate species often require or flower most rapidly in the long daylengths, or photoperiods, experienced in summer or after prolonged periods of cold temperatures, referred to as vernalization. Yet, even within species, plants vary in the degree of responsiveness to these cues. In , () and () genes are key to photoperiod and vernalization perception and antagonistically regulate () to influence the flowering time of the plants. However, it is still an open question as to how these genes vary in their interactions among wild accessions with different flowering behaviors and adapted to different microclimates, yet this knowledge could improve our ability to predict plant responses in variable natural conditions. To assess the relationships among these genes and to flowering time, we exposed 10 winter-annual accessions from throughout Norway, ranging from early to late flowering, along with two summer-annual accessions to 14 weeks of vernalization and either 8- or 19-h photoperiods to mimic Norwegian climate conditions, then assessed gene expression levels 3-, 5-, and 8-days post vernalization. and explained both levels and flowering time (days) but not rosette leaf number at flowering. The correlation between and flowering time increased over time. Although vernalization suppresses , was high in the late-flowering accessions. Across accessions, was expressed only at low levels and did not respond to in the late-flowering accessions. We proposed that may only be expressed below a threshold value of and demonstrated that these three genes correlated to flowering times across genetically distinct accessions of .