Isolation and characterisation of rhizosphere bacteria active against Meloidogyne incognita, Phytophthora nicotianae and the root knot-black shank complex in tobacco

BACKGROUNDThe use of dually antagonistic bacteria (DAB) as alternatives to chemicals for biological control of disease complexes has received little attention. In this study targeting the Meloidogyne incognita-Phytophthora nicotianae complex, DAB from the tobacco rhizosphere were identified and screened against the diseases caused by one or both pathogens in tobacco. RESULTSFrom 450 soil tobacco rhizosphere samples, 26 DAB were identified and had in vitro nematicidal and antifungal efficacies of 37.2-100% and 32.9-73.4% respectively. These DAB were classified into 19 species of 11 genera. In pot experiments, Streptomyces flavofunginiSNA26, Pseudomonas putidaSNB53 and Serratia marcescens subsp. sakuensisSNB54 effectively suppressed black shank (control effect 72.0-80.2%), root knot (70.0-81.7) and the disease complex (58.7-68.5%) caused by P. nicotianae, M. incognita and both pathogens in tobacco respectively. CONCLUSIONNineteen DAB species were demonstrated to be antagonists against the M. incognita-P. nicotianae complex. Because S. flavofunginiSNA26, P. putidaSNB53 and S. marcescens subsp. sakuensisSNB54 significantly suppressed the infection of M. incognita and P. nicotianae in tobacco, these species have potential for development as biocontrol agents against the diseases and complex caused by these two pathogens. (c) 2014 Society of Chemical Industry