Isolation and Functional Characterization of Two SHORT VEGETATIVE PHASE Homologous Genes from Mango

The SHORT VEGETATIVE PHASE (SVP) gene is a transcription factor that integrates flowering signals and plays an important role in the regulation of flowering time in many plants. In this study, two full-length cDNA sequences of SVP homologous genes-MiSVP1 and MiSVP2-were obtained from 'SiJiMi' mango. Sequence analysis showed that the MiSVPs had typical MADS-box domains and were highly conserved between each other. The analysis of expression patterns showed that the MiSVPs were expressed during flower development and highly expressed in vegetative tissues, with low expression in flowers/buds. The MiSVPs could responded to low temperature, NaCl, and PEG treatment. Subcellular localization revealed that MiSVP1 and MiSVP2 were localized in the nucleus. Transformation of Arabidopsis revealed that overexpression of MiSVP1 delayed flowering time, overexpression of MiSVP2 accelerated flowering time, and neither MiSVP1 nor MiSVP2 had an effect on the number of rosette leaves. Overexpression of MiSVP1 increased the expression of AtFLC and decreased the expression of AtFT and AtSOC1, and overexpression of MiSVP2 increased the expression levels of AtSOC1 and AtFT and decreased the expression levels of AtFLC. Point-to-point and bimolecular fluorescence complementation (BiFC) assays showed that MiSVP1 and MiSVP2 could interact with SEP1-1, SOC1D, and AP1-2. These results suggest that MiSVP1 and MiSVP2 may play a significant roles in the flowering process of mango.