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.
ABSTRACT
KEY MESSAGE: Overexpression of grapevine VvABF2 gene could enhance osmotic stress tolerance in Arabidopsis thaliana but fully required for ABA signaling. The abscisic acid (ABA)-dependent AREB/ABF-SnRK2 pathway has been demonstrated to play a pivotal role in response to osmotic stress in model plants. However, its function in other specific species, for example grapevine, has not been fully characterized. In this study, grapevine (Vitis vinifera L.) ABSCISIC ACID RESPONSE ELEMENT-BINDING FACTOR2 (VvABF2), a homologous gene of AREB/ABFs form Arabidopsis, was isolated and constitutively expressed in Arabidopsis under the control of the cauliflower mosaic virus 35S promoter. The VvABF2 transgenic Arabidopsis plants showed to be more sensitive to exogenous ABA compared to wild type plants and exhibited significant osmotic tolerance, like polyethylene glycol (PEG) and drought but fully required ABA for signaling. This fact was further confirmed by its downstream gene expression assays. In addition, the determination of ROS antioxidant enzymes (including SOD, POD and CAT) and the MDA of transgenic lines indicated that overexpression of VvABF2 in Arabidopsis significantly increased ROS scavenging ability and thereby reduced the cell membrane damage, which might be ABA-independent. Our results provide evidence that VvABF2 has a similar function to the Arabidopsis homolog in response to osmotic stresses, and that there is a similar ancestral function of this gene in ABA-dependent response to stresses in grapevine.
