Cell wall/vacuolar inhibitor of fructosidase 1 regulates ABA response and salt tolerance in Arabidopsis.

ABA regulates abiotic stress tolerance in plants via activating/repressing gene expression. However, the functions of many ABA response genes remained unknown. C/VIFs are proteinaceous inhibitors of the CWI and VI invertases. We report here the involvement of C/VIF1 in regulating ABA response and salt tolerance in Arabidopsis. We found that the expression level of C/VIF1 was increased in response to ABA treatment. By using CRISPR/Cas9 gene editing, we generated transgene-free c/vif1 mutants. We also generated C/VIF1 overexpression plants by expressing C/VIF1 under the control of the 35S promoter. We examined ABA response of the 35S:C/VIF1 transgenic plants and the c/vif1 mutants by using seed germination and seedling greening assays, and found that the 35S:C/VIF1 transgenic plants showed an enhanced sensitivity to ABA treatment in both assays. On the other hand, the c/vif1 mutants showed slight enhanced tolerance to ABA only at the early stage of germination. We also found that salt tolerance was reduced in the 35S:C/VIF1 transgenic plants in seed germination assays, but slightly increased in the c/vif1 mutants. Taken together, our results suggest that C/VIF1 is an ABA response gene, and C/VIF1 is involved in the regulation of ABA response and salt tolerance in Arabidopsis.