Plant growth promoting properties of root microbiome and multispecies interactions in plant holobionts at the level of microbial communities and metabolites

Abstract

Plants host multispecies microbial communities in and around their roots, and these root-associated microbes are important for the growth and development of plants. Through exudation, plants release up to 40% of their photosynthetically fixed carbon along with other chemical compounds in their surrounding soil. These chemical compounds help in the selection of a distinct root microbial community. Certain members of this root microbial community are considered as plant growth promoting bacteria as they help plants in nutrient acquisition, disease suppression, stress tolerance, growth promotion. Hence studying these microbial communities are of great interest as the knowledge can help us develop novel agricultural tools. But it remains challenging to study the interaction between multispecies root microbial community and plants under controlled conditions. In this study, we have developed a plant holobionts assay with Brassica oleracea var. alboglabra and used multispecies root microbial community to show plant growth promoting properties under controlled conditions. We have also reported the presence of plant growth promoting metabolic pathways in case of plants grown with root associated microbiome through metabolic profiling and analysis. Our study showed that root associated microbiota helps plant in better growth (fresh weight gain, root elongation, and secondary root growth) and development under nutrient-poor conditions (0.8% w/v water agar) in the controlled environment. The developed plant holobionts assay has the potential to serve as an important platform to test different root microbial communities for their PGP properties under controlled lab conditions by allowing concurrent metabolomics and metagenomics analysis.