Isolation, screening and molecular characterization of free-living bacteria of potato (Solanum tuberosum L.) and their interplay impact on growth and production of potato plant under Mycorrhizal association

Abstract

Plant growth promoting rhizobacteria (PGPR) are associated both with the rhizosphere and/or may be non-rhizospheric. The present study isolation, screening and molecular characterisation of PGPR from the potato cultivars Kufri sindhuri, Kufri chipsona-3 and Kufri lauvkar. These isolates were screened for their traits like production of indole acetic acid (IAA), ammonia, hydrogen cyanide (HCN), siderophore presence, phosphate solubilisation (P-solubilisation) and also antifungal activity. All the bacterial isolates were found positive for P-solubilisation, IAA, ammonia and siderophore production. Bacillus amyloliquefaciens followed by Pseudomonas brassicacearum showed highest P-solubilisation and IAA production whereas HCN production was found in three isolates. Certain species of Bacillus and Pseudomonas were showing antifungal activity against Pythium sp. and Fusarium sp. Phylogentic relationship among the identified PGPR as a phylogenetic tree was generated by neighbour joining approach with the help of MEGA 6.06 version and UPGMA dendogram constructed. When compared PGPR isolates, PB12, PR3 and PR1 were found to be closely associated and PB10 and PB11 were distantly related. Mycorrhizal fungi are symbionts forming mutualistic relationship with plant roots. In this study, surface-sterilized potato tubers were sown in earthen pots filled with sterile soil. Pots were inoculated with AMF along with the PGPRs and another half without any AMF and PGPRs inoculation representing control. Inoculation was done twice 3 days before sowing the tubers and on the onset of seedling emergence. Plants along with their controls were sampled at 90 days after planting (DAP). The potato growth parameters including the tuber yield had increased by using arbuscular mycorrhizal fungi (AMF) bioinoculants in interplay with PGPRs under pot culture conditions. AMF and PGPRs are environmentally friendly and are known to offer sustainable approach in increasing the production of crop.