FLOWERING PROMOTING FACTOR1 Family Proteins Coordinate Seasonal Growth and Development

Abstract Flowering plant development is dependent on sensing seasonality through environmental stimuli such as photoperiod, light quality, and temperature. Length of daylight regulates the expression of florigen, FLOWERING LOCUS T (FT), a mobile protein that moves from leaf phloem companion cells to the shoot apical meristem to initiate flowering in Arabidopsis. In long-day photoperiods with natural red/far-red light conditions (R:FR = 1.0-1.2), FT-expressing cells also express FPF1-LIKE PROTEIN 1 (FLP1), which encodes a potentially mobile protein that induces flowering and stem growth. FLOWERING PROMOTING FACTOR 1 (FPF1) homologs found across a variety of plant species control flowering, growth, or both, often through phytohormonal pathways involving gibberellin or auxin signaling. FPF1 genes in Arabidopsis, tobacco, mango, cotton, barley, and Brachypodium regulate flowering time, while FPF1 homologs in tomato and rice regulate stem and root development. FPF1’s role in plant development is compelling, given its ability to regulate flower and stem growth, yet a comprehensive review of this gene family does not yet exist. Although FPF1 genes share the similarity of regulating development, little is known of how this is achieved mechanistically. Here, we synthesize literature on the function of FPF1-related genes across plant species over the past several decades, and we discuss the implications of these genes in influencing plant development in response to seasonal environmental conditions.