| 【O bjective】New and efficient biocontrol suspensions that could prevent fruit postharvest diseases such
as litchi downy blight were screened out to reduce the loss of litchi during transportation and delay browning, and reveal the relevant physiological mechanisms of biocontrol efficacy.【Method】The bacterial suspensions of Bacillus amyloliquefaciens
PP19 and Exiguobacterium acetylicum SI17 were sprayed onto the litchi fruit for pre-treatment at the postharvest in the
laboratory. Then, a suspension of Peronophythora litchii（SC18）24 hours after pre-treatment. Subsequently, the disease
severity of litchi fruit was observed and the enzyme activity or substance contents corresponding to peel at different time
points were detected.【Result】The suspensions of PP19 and SI17 significantly reduced the litchi downy blight, and the
control efficacy of PP19 was 39.59%-88.76% while that of SI17 was 18.08%-91.01%. Their bacterial suspensions increased
the activities of CAT, SOD, GLU, PAL and PPO in peel and the content of anthocyanin while decreased the activity of
anthocyanidase and the content of H2O2
and total phenol in peel. SI17 increased much more chitinase activity compared
with that of PP19.【Conclusion】According to the results mentioned above, it is speculated that the effect of two biocontrol
suspensions on disease prevention may be related to the change of related enzyme activities or substance contents to disease
resistance in peel. |
