Indole-3-acetic acid-producing Pantoea strain MTP 17 and Glomus mosseae synergistically improve the growth, yield and bacoside content of Bacopa monnieri

The present study aimed to evaluate the performance of Indole-3-acetic acid-producing bacteria (IPB) and arbuscular mycorrhizal fungi (AMF) in compatible form for early establishment and higher growth, yield, and secondary metabolite content of vegetatively propagated Bacopa monnieri plants. Four species of Glomus, viz., G. mosseae (Gm), G. aggregatum (Ga), G. fasciculatum (Gf), G. intraradices (Gi), and two Indole-3-acetic acid-producing bacteria (IPB), Bacillus mojavensis (Bm), and Pantoea sp. (Pt) were evaluated individually and in combinations in a pot experiment. Various plant growth parameters like height, biomass, NPK uptake, mycorrhizal colonization, bacterial population in the rhizosphere, phosphatase activity, and bacoside-A content were determined and found to vary with different treatments. Among all the treatments, plants inoculated with Gm + Pt performed better than any other treatment or un-inoculated control. The performance of the consortium of Gm + Pt was further validated in a field experiment on the same parameters. A clear synergistic interaction between Gm and Pt was observed as Pt enhanced rooting and subsequently improved the colonization and spore population of Gm. On the other hand, the presence of Gm improved the population of Pt in the rhizosphere. The presence of both microbes improved the bacoside-A yields in B. monnieri. The results of this experiment indicate the compatibility and synergy between G. mosseae and Pantoea sp. and suggest using this microbial consortium for plant propagation and growth enhancement while improving soil biological health.