Exogenous H2S promoted osmoregulatory capability via PpWRKY11-mediated transcriptional activation of PpGAD1 in cold-stored peach fruit.

The mechanisms by which hydrogen sulfide (H2S) treatment alleviates chilling injury (CI) in cold-stored peach fruit through the enhancement of osmoregulatory substances accumulation require further investigation. Exogenous H2S treatment increased the levels of osmolyte-related amino acids (glutamate (Glu), ornithine (Orn), and arginine (Arg)); enhanced the activity of γ-Aminobutyric acid (GABA) metabolism-related enzymes and expression of PpGAD1, PpGAD2, and PpGABA-T; and elevated activity of polyamines (PAs) metabolism-related enzymes and expression of PpADC, PpODC, PpPAO1, and PpPAO2, ultimately leading to the accumulation of GABA and PAs (putrescine (Put), spermidine (Spd), and spermine (Spm)). Previous studies have identified PpWRKY11 as responsive to H2S treatment. This study demonstrated the transcriptional activation capacity of PpWRKY11 through transcriptional activity assays. Furthermore, PpWRKY11 positively regulates PpGAD1 expression, as evidenced by dual-luciferase reporter (DLR) assay and binds to the W-box motif in the PpGAD1 promoter, as confirmed by electrophoretic mobility shift assay (EMSA). In summary, exogenous H2S treatment enhanced the accumulation of GABA and PAs. Additionally, PpWRKY11, by binding to the W-box motif, positively regulates PpGAD1 expression, thereby mitigating CI in cold-stored peach fruit.