Synergistic action of rhizobacteria and mycorrhizal fungus against Meloidogyne incognita

Our microbial consortium consisted of two rhizobacteria ( Bacillus thuringiensis and Azotobacter chroococcum ) and one Arbuscular mycorrhizal fungi which were tested against root knot nematode , M. incognita . The results of the compatibility studies revealed that the two rhizobacterial cultures were compatible with each other and that they did not affect the germination of AMF spores. Further, both rhizobacterial cultures were found to be effective against M. incognita under in-vitro conditions. Results from the green house experiment showed that a significant reduction in nematode population and root gall index was recorded in the combined inoculation of all the microbial inoculants . Besides, defense genes such as Phenyl Alanine Ammonia Lyase and lipoxygenase were expressed at a greater level in microbial inoculated tomato roots. Furthermore, rhizobacterial metabolites revealed that among the 67 compounds, only four metabolites such as., p-Methylbenzeneboronic acid, Octadecanoic acid , 2-Hydroxychalcone, and Octadecanoic acid 2-hydroxy-1,3-propanediyl ester were reported in both bacterial cultures. Moreover, nematicidal group of compounds such as fatty acyls, fatty acids, carboxolic acids, benzoic acid and their derivatives were predominantly observed in both the cultures. • Synergistic action of rhizobacteria and AM fungi against M. incognita was reported. • Rhizobacteria and AM fungi significantly reduced the M. incognita population and root gall in tomato. • Defense genes, PAL and LOX were up-regulated in tomato inoculated with rhizobacteria and AM fungi. • Anti- nematicidal compounds, fatty acids, fatty acyls, carboxylic acid were found in rhizobacterial isolates.