In deciduous fruit trees in which dormancy is induced by low temperatures, the expression of DORMACY-ASSOCIATED MADS-BOX genes (DAM) is regulated by CBF/DREB1 transcription factors. In Vitis vinifera, in which dormancy is induced by the photoperiod, VvDAM-SVPs gene expression is regulated by FLOWERING LOCUS T (VvFT). Using the sequences of the six peach (Prunus persica) DORMACY-ASSOCIATED MADS-box genes (DAM) as query, eight putative DAM genes belonging to the family of MADS-box transcription factors and related to the Arabidopsis floral regulators SHORT VEGETATIVE PHASE (SVP) and AGAMOUS LIKE 24 (AGL24) were identified in the V. vinifera genome. Among these, five belong to the subfamily SVP-like genes which have been associated with the regulation of flowering and dormancy in annual and perennial plants, respectively. It has been proposed that they play a direct role in the induction and maintenance of endodormancy (ED) through the regulation of the FLOWERING LOCUS T (FT) gene. In the present study, it is demonstrated that in V. vinifera: (1) VvDAM-SVPs genes are not regulated by ABA/low temperature-induced VvCBFs transcription factors as described for other species of deciduous fruit trees. (2) A contrasting expression pattern between VvDAM3-SVP and VvFT was found under different experimental conditions related to the entry and exit of grapevine buds from ED. (3) Overexpression of VvFT in somatic grapevine embryos (SGE) repressed the expression of VvDAM3-SVP and VvDAM4-SVP. Taken together, the results suggest that VvDAM3-SVP could be associated with ED in grapevine buds, and that its expression could be regulated by VvFT.
Keywords: CBF/DREB1; DAM genes; Endodormancy; FLOWERING LOCUS T; Grapevine buds.