Screening,identification,and bioactivity of an endophytic bacterium from tomato against Botrytis cinerea.

An investigation was conducted on the endophytic bacteria in the roots,stems,and leaves of tomato plants collected from the farmlands in Huaibei City of Anhui Province,East China,and the bacterial strains were screened,with their bioactivities against pathogenic fungus Botrytis cinerea determined.The population density of the endophytic bacteria in the roots,stems and leaves of tomato plants was 5.69×105,5.16×105 and 2.83×105 CFU·g-1 fresh weight,respectively.According to the isolation position and phenotype,267 endophytic bacteria strains were isolated from different internal tissues of tomato plants.By using a dual culture technique,11 strains,accounting for about 4.12% of the endophytic bacteria and exhibiting antagonistic activities against B.cinerea,were screened,among which,strain XF136 isolated from tomato stem had the best inhibitory effect,and formed an inhibition zone with a width of 32.2 mm.The XF136 strain was identified as Bacillus amyloliquefaciens,based on its morphological,physiological,and biochemical properties,(G+C) mol%,and 16S rDNA sequence analysis.The laboratory test with the XF136 culture filtrate showed that the filtrate was effective in inhibiting the mycelium growth and spore germination of B.cinerea,and,the higher the filtrate concentration,the stronger the inhibition effect,with the mycelium growth and spore germination of B.cinerea completely inhibited at the filtrate concentration 20%.The pot experiment demonstrated that the prevention efficiency and cure efficiency of 10% culture filtrate of XF136 against tomato gray mould were equivalent to those of 50% Badistan 600-fold dilution,and the control efficiency of 20% culture filtrate of XF136 was superior to that of 50% Badistan 600-fold dilution.This study indicated that the strain XF136 was potentially valuable in the biological control of tomato gray mould,and had favorable development and practical prospects.