Arbuscular mycorrhizal fungi and associated bacteria isolated from salt-affected soil enhances the tolerance of maize to salinity in coastal reclamation soil

Arbuscular mycorrhizal fungi (AMF) have close association with bacteria in establishing a tripartite interaction with plants. The objective of this study was to assess the tripartite interactions among AMF, associated bacteria and maize on enhancing salt stress tolerance. AMF spores isolated from coastal reclamation land were identified as Rhizophagus intraradices and multiplied using monosporic mass culturing. From surface-decontaminated spores of R. intraradices, isolation of associated bacteria was carried out and the obtained isolate was identified as Massilia sp. RK4. The isolated bacterial strain was found to possess several plant growth promoting characteristics and for further studies, its effect on maize plant growth in coastal reclamation soil was evaluated under three different salt concentrations. Salt stress substantially reduced plant growth, root colonization and spore-producing ability of the R. intraradices. However, treatment with the AMF and a combination of AMF and associated bacteria alleviated the salt-induced reduction of plant growth, root colonization, nutrient accumulation and lowered leaf proline levels compared to control treatment. The co-inoculation of R. intraradices and Massilia sp. RK4 exhibited significant impact on AMF root colonization and nutrient accumulation in plants compared to inoculation with R. intraradices only. Inoculation of R. intraradices and Massilia sp. RK4 improved the salinity tolerance of maize through the dual effect exerted by AMF and its associated bacteria.