Soil microbe inoculation alters the bacterial communities and promotes root growth of Atractylodes lancea under heat stress

Atractylodes lancea is a medicinal plant widely used in treating rheumatic diseases, digestive disorders, night blindness, and influenza. Microbes greatly impact plant growth and metabolism. However, the microbiome associated with A. lancea remains unclear. Hence, we aimed at assessing the effect of soil microbe inoculation on A. lancea under heat stress from multiple perspectives, including regulation of growth, valuable secondary metabolites, root endophytic and rhizosphere bacterial communities. A. lancea was inoculated with soil microbes, then grown under normal/high temperature. Biomass, chlorophyll contents, production of major medicinal compounds, physiochemical properties of the soil, and in the composition of root bacterial communities of A. lancea were investigated. Soil microbe inoculation promoted root sink strength, accumulation of medicinal compounds, and attenuated damage caused by heat stress. A. lancea showed preference for the endophytic bacterial genera Rhodococcus, Ralstonia, Dongia Paenibacillus and Burkholderia-Caballeronia-Paraburkholderia post-inoculation, the latter four genera playing important roles in protection from heat stress, with abundance of the latter two specifically positively correlated to medicinal compound production. A. lancea enriched the bacterial genera Saccharimonadales, Novosphingobium and excluded Chitinophaga in its rhizosphere post-inoculation. Soil microbes characteristically promoted A. lancea growth, improved heat stress tolerance, and promoted root medicinal compound accumulation. A. lancea selectively enriched particular endophytic and rhizospheric bacterial communities post-inoculation, possibly due to unique aromatic root exudates. The selected bacteria potentially synergistically improved soil available nutrients and uptake by root. Bacterial species selected by A. lancea root have the potential to serve as biological fertilizers for A. lancea farming.