Spatial and temporal changes in the microbial community associated with postharvest decay in chili pepper fruits

Currently, the control of postharvest decay in chili pepper fruits has mainly focused on the pericarp tissue, whereas studies on decay occurring in the calyx and pedicel regions were lacking. Disease outbreaks are associated with shift in microbial communities. In this study, we investigated the decay characteristics in the pedicel, calyx, and pericarp of peppers during storage and analyzed the richness, diversity, and composition of the bacterial and fungal communities on their surfaces. A considerable variation was observed in the decaying characteristics of the pedicel, calyx, and pericarp in peppers during storage at 30 °C. The pedicel exhibited the highest susceptibility to rotting with a decay rate of 76.67% after 4 days of storage, followed by the calyx and pericarp. The bacteria and fungi on the pedicel, calyx and pericarp tissue surfaces were individually sampled and analyzed using amplicon sequencing. At the beginning of the storage period, the pericarp had the highest microbial richness and diversity, followed by the pedicel and calyx. During storage, bacterial richness decreased on the pericarp but remained stable on the pedicel and calyx. Meanwhile, fungal richness decreased in all three tissues. Analysis of changes in the abundance of genera reveals that Pectobacterium and Enterococcus were responsible for pericarp decay and caused bacterial soft rot disease. Fusarium , a plant pathogen, was identified as the primary cause of pedicel and calyx disease, resulting in mold spots. Functional prediction of bacterial and fungal communities indicated that bacterial microorganisms associated with xylanolysis play important roles in pericarp tissue rot. • Decay characteristics in different parts of green chili peppers were studied. • The pedicel was most susceptible to rotting, followed by the calyx and pericarp. • Pectobacterium and Enterococcus are key contributors to pericarp decay. • Bacteria associated with xylanolysis play an essential role in pericarp rot. • Fusarium was identified as the primary cause of mold spots on pedicels and calyces.