Development of KASP markers for FT family genes in soybean

FLOWERING LOCUS T (FT), a key regulator of photoperiod pathway, plays a pivotal role in modulating flowering time and growth period-related traits in plants. In this study, we identified 10 FT family genes in soybean and examined their functional divergences through sequence alignment analysis. Phylogenetic and amino acid sequence analysis revealed that the 92nd residue and the Segment B domain (sites 129, 131, 134, 135) are the critical determinants of potential functional divergence and activity variation among GmFT. Using the SoyOmics website, we detected natural variations in the genomic and promoter regions of GmFTs, along with numerous haplotypes. By correlating these haplotypes with flowering time, we identified 7 potential KASP markers associated with soybean growth period: GmFT1a-60297360, GmFT1b-60311669, GmFT2a-31695562, GmFT2b-31739433, GmFT3a-4106476, GmFT5a-4078626, and GmFT5b-37490962. All KASP markers exhibited high selection efficiency (97.56%–100.00%) and reliable genotyping accuracy when validated across 82 soybean varieties spanning multiple maturity groups (MGs). This study systematically elucidates the functional divergence of GmFTs and develops efficient KASP markers, providing essential technological support for photoperiod-adaptive breeding and germplasm innovation.