Inhibition of Rhizopus rot in postharvest peach fruit during storage by specific extracellular fragmented self-DNA treatment

Extracellular self-DNA (sDNA), by functioning as a damage-associated molecular pattern (DAMP)-related eco-friendly elicitor, exerts protective defectiveness on conspecific plants against microbial infection. To determine the efficacy of different fragments of peach sDNA in controlling mold decay in postharvest fruit, we extracted and fragmented peach (Prunus persica) sDNA and applied the fragmented sDNA to postharvest peach fruit against necrotrophic pathogen Rhizopus stolonifer. The results showed that the application of fragmented peach sDNA induced length-dependent fungal resistance and that fragmented sDNA from 250 to 750 bp caused the strongest potential for constraining Rhizopus rot and maintaining ovall quality in postharvest peach fruit. The defense induced by specific fragmented sDNA in peach fruit was correlated with accumulated callose and mRNAs of NHL10, FRK1, POD5, MYB51, WRKY11 and CBP60g, indicating that the DAMP-triggered immunity (PTI) response functioned in this case. Moreover, the sDNA-induced PTI response in this case included H2O2 accumulation and MAPK activation, contributing to the intercellular SA signalling cascade and potentiated expression of downstream defence-related genes. Hence, the specific fragmented sDNA can inhibit Rhizopus rot in postharvest peach fruit through the PTI-related defence, and SA cellular signalling is involved in the immune activation during the postharvest period.