Exploration of bacterial endophytes in cucumber (Cucumis sativus L.)


                                In an attempt to explore the potentials of the endophytic bacterial population in cucumber plants, thirty different isolates have been made and tested for its efficacy against damping off the pathogen, Pythium aphanidermatum (Edson) using dual culture technique. The result revealed the potentials of Pseudomonas aeurginosa (MPP EB 4 and MPP EB 3) and Achromobacter denitrificans (MPP EB 8). The isolates MPP EB 3, MPP EB 4 and MPP EB 8 showed the maximum inhibition of 36.7, 40.0 and 32.2 per cent over control, respectively. The convoction of animicrobial compound isolated from selected isolates of MPP EB 3, MPP EB 4 and MPP EB 8 were tested against the pathogen by using agar well diffusion technique, which showed inhibition of 25.2, 43.2 and13.7 per cent over control, respectively. GCMS analysis for the secondary metabolites of P.aeurginosa deciphered an array of compounds, which are known to have antifungal property. Achromobacter denitrificans (MPP EB 8) could not inhibit the pathogen, but enhanced the plant growth up to 57.9 per cent, when compared to control. In addition to suppressing the pathogen, isolate MPP EB4 and MPP EB 3 could increase the growth of cucumber seedlings up to 31.6 and 17.0 per cent over control, respectively. Hence, MPP EB 4 (P.aeuriginosa) could be exploited as endophytic bioinoculant with adequate biosafety measures.

Key words : Cucumber, endophytes, Pseudomonas aeuriginosa, Achromobacter denitrificans, biocontrol and plant growth promotion..

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