Control of postharvest soft rot caused by Erwinia carotovora of vegetables by a strain of Bacillus amyloliquefaciens and its potential modes of action

Abstract

Erwinia carotovora subsp. carotovora (Ecc), the causal agent of bacterial soft rot, is one of the destructive pathogens of postharvest vegetables. In this study, a bacterial isolate (BGP20) from the vegetable farm soil showed strong antagonistic activity against Ecc in vitro, and its twofold cell-free culture filtrate showed excellent biocontrol effect in controlling the postharvest bacterial soft rot of potatoes at 25 °C. The anti-Ecc metabolites produced by the isolate BGP20 had a high resistance to high temperature, UV-light and protease K. Based on the colonial morphology, cellular morphology, sporulation, and partial nucleotide sequences of 16S rRNA and gyrB gene, the isolate BGP20 was identified as Bacillus amyloliquefaciens subsp. plantarum. Further in vivo assays showed that the BGP20 cell culture was more effective in controlling the postharvest bacterial soft rot of green peppers and Chinese cabbages than its twofold cell-free culture filtrate. In contrast, the biocontrol effect and safety of the BGP20 cell culture were very poor on potatoes. In the wounds of potatoes treated with both the antagonist BGP20 and the pathogen Ecc, the viable count of Ecc was 31,746 times that of BGP20 at 48 h of incubation at 25 °C. But in the wounds of green peppers, the viable count of BGP20 increased 182.3 times within 48 h, and that of Ecc increased only 51.3 %. In addition, the treatment with both BGP20 and Ecc induced higher activity of phenylalanine ammonia-lyase (PAL) than others in potatoes. But the same treatment did not induce an increase of PAL activity in green peppers. In conclusion, the present study demonstrated that the isolate BGP20 is a promising candidate in biological control of postharvest bacterial soft rot of vegetables, but its main mode of action is different among various vegetables.

Expression of PR-protein genes and induction of defense-related enzymes by Bacillus subtilis CBR05 in tomato (Solanum lycopersicum) plants challenged with Erwinia carotovora subsp. carotovora

“…The previous studies performed on potato showed that application of B. subtilis against soft rot bacterium, ECC resulted in complete suppression of soft rot disease and were also significantly increased fresh and dry weights. 38,39) Similarly, Zhao et al 40) also found that the biocontrol efficacy of the antagonist B. amyloliquefaciens BGP20 in controlling ECC on green peppers and Chinese cabbages. In the previous study, we also found that B. subtilis CBR05 inoculation had plant growth promotion activities and antifungal activities against Fusarium oxysporum and Rhizoctonia solani.…”

Biological Control Activities of Rice-Associated Bacillus sp. Strains against Sheath Blight and Bacterial Panicle Blight of Rice

“…Strains of B . amyloliquefaciens have been reported as a good biological control agent for other crop diseases, including bacterial wilt and powdery mildew of tomato [ 34 , 37 ], stem rot of canola [ 38 ], bacterial wilt of peanut [ 39 ], ring rot of apple [ 40 ], and bacterial soft rots of vegetables [ 41 ].…”

Trichokonins fromTrichoderma pseudokoningiiSMF2 induce resistance against Gram-negativePectobacterium carotovorumsubsp. carotovorumin Chinese cabbage

“…Therefore, much attention has been focused on the biologic control agents (BCAs), because they are efficient, reliable, and safe for the environment (Lyon & Newton, 1997). Several BCAs have been used for controlling soft rot pathogens, such as Pseudomonas and Bacillus (Geels & Schippers, 1983;Kloepper, 1983;Colyer & Mount, 1984;Raju et al, 2006;Zhao et al, 2013).…”