Cloning, characterization, and ectopic expression in Arabidopsis to determine the function of FvSPL1 gene from woodland strawberry (Fragaria vesca)

BACKGROUND: SQUAMOSA promoter binding protein-like (SPL) proteins are a class of plant-specific transcription factors that play important roles in plant development. However, the majority of SPL genes in strawberry are functionally uncharacterized. OBJECTIVE: To understand the biological functions and elucidate the molecular regulatory mechanisms of SPL genes in strawberry development. METHODS: The FvSPL1 gene from woodland strawberry was cloned and the phylogenetic tree was analyzed using bioinformatics methods. Subcellular localization, transcriptional activity, DNA binding ability and regulatory mechanisms of FvSPL1 were analyzed through biochemical and genetic approaches. RESULTS: Phylogenetic analysis with SPL genes from Arabidopsis, tomato and chrysanthemum indicated that FvSPL1 clustered in the same group as those of the miR156 target site located at the 3'-untranslated region. Further biochemical analysis indicated that FvSPL1 was exclusively localized in the nucleus. Electrophoretic mobility shift assay demonstrated that FvSPL1 could specifically recognize the GTAC motif. Transcriptional activity analysis showed that FvSPL1 is a transcriptional activator that could activate the expression of the FvAP1 gene. Finally, transgenic Arabidopsis overexpressing the FvSPL1 gene exhibited significantly early flowering. Taken together, our study indicated that FvSPL1, similar to its orthologs in Arabidopsis, mainly functions in regulating plant flowering. CONCLUSIONS: These findings provide insight into the mechanism of flowering in strawberry, and contribute to the understanding of strawberry flowering time manipulation which will facilitate the molecular breeding of strawberries.