The 14–3–3 gene AaGRF1 positively regulates cold tolerance in kiwifruit

Low temperatures severely threaten the growth and development of kiwifruit. Research has demonstrated that proteins belonging to the 14–3–3 family play a pivotal regulatory function in the ability of plants to resist stress. However, this specific roles of the genes in kiwifruit cold tolerance remain unclear. It had been identified that β-amylase gene, AaBAM3.1, exhibits a positive regulatory effect on kiwifruit's tolerance to low temperature. In our research, we obtained the Actinidia arguta 14–3–3 gene general regulatory factor 1 (AaGRF1) from yeast one-hybrid (Y1H) screening library of the AaBAM3.1 promoter; the expression level of AaGRF1 was enhanced by low-temperature stress. Subcellular localization, Y1H and dual-LUC assay indicated that the AaGRF1 protein resides within the nucleus and possesses the ability to interact with the AaBAM3.1 promoter. Moreover, we also studied the role of AaGRF1 gene in cold resistance of kiwifruit. When AaGRF1 was overexpressed in kiwifruit, the transgenic plants exhibited enhanced cold tolerance. The level of antioxidants and soluble sugars in these plants were elevated compared to wild-type (WT) lines. RNA-seq of the transgenic and WT lines revealed that AaGRF1 might interact with genes in the ‘ascorbate-glutathione’ and ‘starch and sucrose’ pathways, thereby enhancing the cold resistance of kiwifruit. In summary, we hypothesize that the 14–3–3 gene AaGRF1 may positively modulate the cold resistance in kiwifruit by accumulating more antioxidants and soluble sugars.