14-3-3 proteins regulate the HCHO stress response by interacting with AtMDH1 and AtGS1 in tobacco and Arabidopsis

Formaldehyde (HCHO) is one of the most essential common carcinogenic environmental pollutants. While 14–3–3 proteins are known to regulate the response of plants to HCHO stress, the regulatory mechanisms responsible for a tolerant phenotype remain unclear. We first performed qPCR analysis of HCHO-treated Arabidopsis and tobacco and determined that the expression of At14–3–3PSI and Nt14–3–3C genes was rapidly upregulated after HCHO stress. Furthermore, overexpression of 14–3–3, AtMDH1 or AtGS1 genes enhanced plant HCHO absorption capacity and resistance, and knockdown or knockout of 14–3–3, AtMDH1 or AtGS1 genes reduced plant HCHO absorption capacity and resistance. However, overexpression of the AtGS1 and AtMDH1 genes in the At14–3–3 psi mutant restored HCHO uptake and resistance in Arabidopsis. Moreover, 14–3–3 bound to the N-terminus of AtMDH1 and the C-terminus of AtGS1, respectively, and repressed and enhanced their expression. The 13C NMR results of HCHO stress mutants Atgs1 and Atmdh1 showed that the metabolites Glu and Asp rapidly increased, indicating that AtGS1 and AtMDH1 were indeed indispensable for Arabidopsis to metabolize HCHO. In conclusion, we uncovered a HCHO stress response mechanism mediated by 14–3–3, which enhances the plant's ability to absorb HCHO, deepening our understanding of how plants respond to HCHO stress.