Evaluation of Pseudomonas fluorescens strains for biological control of root-knot nematode in some tomato cultivars

The root-knot nematode, Meloidogyne javanica, is one of the major tomato pathogens in Iran. In the current study, Pseudomonas fluorescens UTPF101 and UTPF68 strains were evaluated for biological control of the pathogen. The strains were studied in terms of having phlD gene through polymerase chain reaction (PCR). The ability of bacteria to produce antimicrobial metabolites and their effect on hatching eggs and larvicidal activity were then studied in vitro. Finally, the ability of bacteria to control nematode on four varieties of tomatoes was studied via a factorial experiment in a randomized complete block design with four replications under greenhouse conditions. PCR procedure results showed that both strains contained phlD gene and 629 bp DNA fragment was reproduced in both of them. Bacterial strains were capable of producing DAPG antibiotic, hydrogen cyanide and protease in in vitro conditions. UTPF68 strain showed a greater impact on the egg hatching compared to strain UTPF101, while in terms of the impact on larvae mortality; both strains performed the same. The greenhouse results indicated that both bacterial strains increased the growth factors and reduced nematode pathogenicity in the infected plants. The rate of growth or controlling nematode was different depending on tomato cultivar or bacterial strain.