No abstract

SQUAMOSA-promoter binding protein-like (SPL) proteins are plant-specific transcript factors that play essential roles in plant growth and development. Although many SPL genes have been well characterized in model plants like Arabidopsis, rice and tomato, the functions of SPLs in strawberry are still largely elusive. In the present study, we cloned and characterized FvSPL10, the ortholog of AtSPL9, from woodland strawberry. Subcellular localization shows FvSPL10 localizes in the cell nucleus. The luciferase system assay indicates FvSPL10 is a transcriptional activator, and both in vitro and in vivo assays indicate FvSPL10 could bind to the promoter of FvAP1 and activate its expression. Ectopic expression of FvSPL10 in Arabidopsis promotes early flowering and increases organs size. These results demonstrate the multiple regulatory roles of FvSPL10 in plant growth and development and lay a foundation for investigating the biological functions of FvSPL10 in strawberry.

WRKY protein is one of the largest plant-specific transcription factors that plays critical roles in plant stress responses, but few WRKY transcription factors have been functionally analyzed in strawberry. In this study, a Botrytis cinerea response WRKY gene, FvWRKY50, was isolated from the woodland strawberry. Expression analysis indicated that the transcript of FvWRKY50 was gradually decreased with fruit ripening, but was significantly induced by B. cinerea infection in mature strawberry fruit. Subcellular localization assay revealed that FvWRKY50 was localized in the nucleus. Several cis-elements related to pathogen responses were observed in the promoter region of FvWRKY50. Pathogen infection assay indicated that overexpression of FvWRKY50 in strawberry fruit significantly enhanced their resistance against B. cinerea, while the silencing of FvWRKY50 dramatically compromised their disease-resistant ability. The expression levels of several genes involved in jasmonic acid (JA) biosynthesis, signaling transduction, and antimicrobial protein biosynthesis were regulated to diverse extents in FvWRKY50 overexpressed and silenced fruit. Collectively, our study inferred that FvWRKY50 is a positive regulator that mediates resistance against B. cinerea through regulating some JA pathway and defense-related genes.

SQUAMOSA promoter binding protein-like (SPL) proteins is a class of plant specific transcription factors that play important roles during plant development. However, the majority of SPL genes in strawberry are functionally uncharacterized. In this study, three SPL genes, i.e. FvSPL1, FvSPL2, and FvSPL11 (FvSPL1/2/11), from woodland strawberry were cloned and characterized. Phylogenetic analysis with SPL genes from Arabidopsis, tomato and chrysanthemum indicated that FvSPL1/2/11 were clustered into the same group with those of miR156 target site located at the 3’-untranslated region (UTR). Further biochemical analysis indicated that FvSPL1 was exclusively localized in the nucleus. Electrophoretic mobility shift assay demonstrated FvSPL1 could specifically recognized the GTAC motif. Transcriptional activity analysis showed FvSPL1 was a transcriptional activator that could activate the expression of FvAP1 gene. Finally, all of the transgenic Arabidopsis that overexpression the three FvSPL genes were exhibited significantly early flowering phenotype. Taken together, our study indicated that FvSPL1/2/11 similar to their orthologs in Arabidopsis mainly functions in regulating plant flowering. These results enriched our understanding to the functions of SPL genes in strawberry and might be utilized for strawberry flowering time manipulation in the future.