Efficiency of cucumber endophytic bacteria on Meloidogyne javanica control under lab and greenhouse conditions

Root-Knot nematode, Meloidogyne javanica is currently proposed as an important problem in the cucumber greenhouses of the country. In the present study, endophytic bacteria were evaluated to control the root-knot nematode.Seventy strains were isolated from cucumber roots, gathered from fields and greenhouses in Razavi Khorasan province.Based on the results of biological assays, seven representative strains showing the highest values of second instar larvae mortality and inhibition of egg hatching, were selected for greenhouse experiments. These bacterial strains were examined in terms of reduction of pathogenicity indexes and disease severity. Strains Fm1, Em1 and Y15 were evaluated significantly positive in reduction of egg, gall and second instar larvae number on infected cucumber roots. Moreover, the lowest level of gall index was obtained following the application of these strains compared to the control (only nematode). According to 16S rDNA gene sequencing, three selected strains associated to greenhouse trials belonged to Pseudomonas rhodesiae (Fm1 and Em1) and Acinetobacter sp. (Y15). Consequently, strains Fm1, Em1, and Y15 can be suggested as sufficient candidates in order to perform more studies on the root knot nematode repression in natural conditions.