LAUSR

Photoperiod responsiveness is a key factor limiting the geographic distribution of cultivated soybean and its wild ancestor. In particular, the genetic basis of the adaptation in wild soybean remains poorly understood. Here, we identified the novel locus Time of Flowering 5 (Tof5), which promotes flowering and enhances adaptation to high latitudes in both wild and cultivated soybean, and determined that it encodes a homologue of Arabidopsis thaliana FRUITFULL (FUL). Importantly, we suggest that different alleles of Tof5 have undergone parallel selection. The Tof5H1 allele was strongly selected by humans after the early domestication of cultivated soybean, while Tof5H2 allele was naturally selected in wild soybean, and in each case facilitating adaptation to high latitudes. The key flowering repressor E1 suppress the transcription of Tof5 by binding to its promoter. In turn, Tof5 physically associate with the promoters of two important FLOWERING LOCUS T (FT), FT2a and FT5a, to upregulate their transcription and promote flowering under long photoperiods. Our findings provide insight into how wild soybean adapted to high latitudes through natural selection, and indicate that cultivated soybean underwent changes in the same gene but involving a distinct allele that was artificially selected after domestication.