Comparative analysis of the NF-Y transcription factor family identifies VaNF-YA6 as a positive regulator of salt and drought tolerance in grapevine

Nuclear factor Y transcription factors (NF-Y TFs) play crucial roles in plant responses to abiotic stress. However, there is a lack of research on the comparative analysis of evolutionary relationships, real-time quantitative fluorescence PCR (RT-qPCR), and functions of NF-Y TFs to screen key NF-Y TFs that are resistant to salt and drought stresses between Vitis vinifera (V. vinifera) and Vitis amurensis (V. amurensis). In this study, 27 and 26 NF-Y TFs were identified in V. vinifera and V. amurensis, respectively, and were divided into three subgroups. Subcellular localization prediction revealed that NF-Ys TFs were mainly located in the nucleus. Interestingly, the NF-YA protein sequence of ‘NTKKLDWEFWGCCDDCEKWFGGCC’ was lost in the V. vinifera compared to V. amurensis, whereas the sequence ‘SSVYSQPWWGHSIVCVA’ was gained, thus, these sequences might be closely related to the functions performed. RT-qPCR analysis of ‘Pinot Noir’ (cultivated variety) and ‘Zuoyouhong’ (wild variety) plantlets demonstrated that the expression levels of VaNF-YA6, VaNF-YB5, VvNF-YA3, VvNF-YA5, and VvNF-YC2 were significantly upregulated under 400 mmol·L^-1 NaCl and 10% PEG treatments for 24 h Subcellular localization showed that the VaNF-YA6-GFP fusion protein was functioned primarily in the nucleus. Overexpression of VaNF-YA6 in grapevine leaves and Arabidopsis thaliana (Arabidopsis) could significantly enhance tolerance to salt and drought stresses by improving VvSOS2, VvSOS3, VvABF3, VvCPK6 expression levels, enzyme activities, and other protective substances. In summary, our study provides a theoretical basis for the further use of VaNF-YA6 to improve salt and drought resistance in grapevines.