Suppression of fruit decay and maintenance of storage quality of litchi by Photorhabdus luminescens Hb1029 treatment

•Photorhabdus luminescens (PL) retarded pericarp browning of litchi.•PL declined fruit decay and maintained better quality of litchi pulp.•PL increased defense-related enzyme activities.•PL enhanced fruit trehalose accumulation.•PL inhibited malondialdehyde and hydrogen peroxide. Photorhabdus luminescens Hb1029, a nematode symbiotic bacteria, has been found to control litchi fungus disease in vitro, but very limited information is available about fruit postharvest. Litchi fruits cv. Guiwei were treated with 108 CFU mL−1P. luminescens suspension or sterile water as the control and stored at 25±1 °C with 40%–50% relative humidity. The changes in fruit decay, quality maintenance, defense-related enzyme activities and those involved in reactive oxygen species (ROS) were monitored. The results showed that P. luminescens effectively repressed fruit decay, mainly expressed as a significant reduction in browning index and weight loss. Meanwhile, litchi treated with P. luminescens maintained higher total soluble solids, titratable acidity, total soluble sugars and vitamin C compared to the control. Moreover, P. luminescens treatment enhanced the defense enzyme activities (peroxidase, superoxide dismutase and catalase) and induced a significant increase in trehalose content in fruit pulp while a significant decrease in malondialdehyde (MDA), hydrogen peroxide (H2O2) accumulations in pericarp. These findings indicated that, the application of P. luminescens enhanced the defense-related mechanism and non-enzymatic antioxidant system (trehalose, MDA, ROS and H2O2) of litchi against fruit decay.