Analysis of promoter activity reveals that GmFTL2 expression differs from that of the known Flowering Locus T genes in soybean

Regulation of flowering is one of the key issues in crop yield. The Flowering Locus T (FT) gene is a well-known florigen, which integrates various signals from multiple flowering-regulation pathways to initiate flowering. We previously reported that there are at least six FT genes (GmFTL1-6) in soybean displaying flowering activity. However, the individual functions of genes GmFTL1-6 remain to be identified. In this study, we cloned the GmFTL2 promoter (GmFTLpro) from soybean (Glycinemax) cultivar Tianlong 1 and analyzed its motifs bioinformatically and its expression patterns using both a transgenic approach and quantitative RT-PCR (qRT-PCR). In GmFTLpro::GUS transgenic lines, GUS signals were enriched in cotyledons, hypocotyledons, pollen, embryos, and root tips in a photoperiod-independent manner. qRT-PCR confirmed the GUS reporter results. Our results suggest that GmFTL2 expression is regulated by developmental and tissue-specific clues and plays roles in seedling establishment and the development of microgametophytes, embryos, and roots.