Sequential action of FRUITFULL as modulator of the activity of the floral regulators SVP and SOC1

[EN] The role in flowering time of the MADS-box transcription factor FRUITFULL (FUL) has been proposed in many works. FUL has been connected to several flowering pathways as a target of the photoperiod, ambient temperature, and age pathways and it is has been shown to promote flowering in a partially redundant manner with SUPPRESSOR OF OVEREXPRESSION OF CONSTANS 1 (SOC1). However, the position of FUL in these genetic networks, as well as the functional output of FUL activity during floral transition, remains unclear. In this work, a genetic approach has been undertaken to understand better the functional hierarchies involving FUL and other MADS-box factors with well established roles as floral integrators such as SOC1, SHORT VEGETATIVE PHASE (SVP) or FLOWERING LOCUS C (FLC). Our results suggest a prominent role of FUL in promoting reproductive transition when photoinductive signalling is suppressed by short-day conditions or by high levels of FLC expression, as in non-vernalized winter ecotypes. A model is proposed where the sequential formation of FUL–SVP and FUL–SOC1 heterodimers may mediate the vegetative and meristem identity transitions, counteracting the repressive effect of FLC and SVP on flowering. We thank Francisco Madueno and Jose Antonio Jarillo for critical reading of the manuscript and their helpful comments and suggestions. Our work was supported by grants BIO2009-09920 from the Spanish Ministerio de Ciencia e Innovacion and BIO2012-32902 from the Spanish Ministerio de Economia y Competitividad to CF. VB was supported by a doctoral fellowship of the Generalitat Valenciana. Balanzá Pérez, V.; Martinez-Fernandez, I.; Ferrandiz Maestre, C. (2014). Sequential action of FRUITFULL as modulator of the activity of the floral regulators SVP and SOC1. Journal of Experimental Botany. 65(4):1193-1203. https://doi.org/10.1093/jxb/ert482