Chitinolytic microbes confer Meloidogyne incognita resistance and augment secondary metabolites in Bacopa monnieri (L.) Pennell

Abstract

Meloidogyne incognita (Kofoid and White) Chitwood a calamitous plant pathogen affects almost all the commercial crops, especially medicinal plants viz. Bacopa monnieri L. In this study, the efficacy of indigenous chitinolytic microbes against M. incognita in B. monnieri was evaluated under sterilised and natural soil conditions. The plant growth was observed for various parameters viz. nutrient uptake, phytochemical activities and secondary metabolites (bacoside). In the natural soil under green house conditions, the isolates significantly (P ≤ 0.05) reduced M. incognita infestation (1.38–2.78-folds) with significant increase in secondary metabolites (1.28–1.88-fold) over the untreated control. The potential strains were identified through 16S-rRNA as Streptomyces sp., Microbacterium arabinogalactanolyticum, Cellulosimicrobium cellulans, Actinomycetales bacterium, Chitiniphilus sp. and Flavobacterium johnsoniae. These findings thus highlight the potential of indigenous chitinolytic microbes that can be utilised for overall fitness of the plant along with the reduced root-knot nematode infestation in B. monnieri.

Keywords:

• Chitinolytic microbes
• Bacopa monnieri
• galling index
• Meloidogyne incognita
• nematicidal
• secondary metabolites

Acknowledgements

The authors are grateful to the Director, CSIR-CIMAP for providing necessary facilities and Academy of Scientific and Innovation Research (AcSIR-CIMAP), India. Help rendered by Dr Alok Kalra for identification of microbes is highly acknowledged. RG is also thankful to Dr Ashutosh Awasthi for his help during some statistical analysis.