生防细菌PP19和SI17菌悬液对荔枝霜疫病的防病作用初探

Preliminary Study on Biocontrol Effect of the Bacterial Suspension of PP19 and SI17 Against Litchi Downy Blight

【目的】筛选新型高效的生防有益细菌防治果树病害如采后荔枝霜疫病,减少在运输过程中的损失,延缓褐变;揭示生防菌发挥防病作用的可能机制。【方法】将前期优选的生防解淀粉芽孢杆菌(Bacillus amyloliquefaciens)PP19和生防乙酰微小杆菌(Exiguobacterium acetylicum)SI17,分别制备其菌体悬浮液,喷雾预处理采后荔枝果实,24 h后喷雾接种霜疫霉菌(Peronophythora litchii)SC18,随后观察果实病害严重度,检测不同时间点果皮对应的酶活性或物质含量。【结果】生防菌PP19和SI17菌悬液均显著降低采后荔枝霜疫病的发生,防效分别达到39.59%~88.76%和18.08%~91.01%;菌悬液提高果皮CAT、SOD、GLU、PAL、PPO活性,增加果皮花色素苷含量;同时,降低果皮花色素苷酶活性、H2O2含量及总酚含量。SI17比PP19更能提高植物几丁质酶活性。【结论】通过上述结果,推测两个生防菌发挥生防效果可能与改变了果皮抗病相关酶活性或物质含量有关。

【Objective】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.