Two FT-like genes of the PEBP family constitute critical regulators of floral transition in Prunella vulgaris

Abstract

The primary medicinal tissues of Prunella vulgaris (Lamiaceae) are its spikes. Elucidating the molecular genetic determinants governing flowering time in P. vulgaris is therefore critical for ensuring the stable production of this herbal resource. Flowering is regulated by multiple exogenous and endogenous signals that ultimately converge on the floral integrator encoded by FLOWERING LOCUS T ( FT ). However, the regulatory network underlying flowering control in P. vulgaris remains largely unexplored. In this study, distinct flowering phenotypes were observed among four geographically distinct populations of P. vulgaris . To dissect the function of FT homologs in this process, we identified a total of 15 genes encoding phosphatidylethanolamine-binding protein (PEBP) within the P. vulgaris genome. Phylogenetic reconstruction coupled with duplication analysis revealed that gene duplication events have given rise to six FT -like paralogs. Subcellular localization assays showed that all six FT-like proteins are dually targeted to the nucleus and the peripheral cytoplasm. Among these, PvuFT1 and PvuFT2 exhibited predominant transcript accumulation in leaves, and their respective heterologous overexpression in Arabidopsis thaliana significantly accelerated floral transition. Furthermore, functional interrogation via a virus-induced gene silencing (VIGS) system, employed to knockdown PvuFT1 and/or PvuFT2 expression in P. vulgaris leaves, demonstrated that these two genes promote flowering in the native host. Collectively, our findings provide compelling evidence for the functional diversification of FT -like genes in the regulation of flowering time and offer a valuable genomic resource for marker-assisted breeding strategies in P. vulgaris.