Epichloe gansuensis symbiosis-induced shifts in root exudation promotes the growth of Achnatherum inebrians via enhancing synergistic effects by beneficial bacteria.

Plant-associated microorganisms can be found in various plant niches and plays an important role in the response to environmental stress. For example, foliar fungal endophytes are known for their ability to increase host resistance to insect pests, fungal pathogens and drought. However, understanding of the effects of Epichloe endophytes on the assembly and ecological function of phyllosphere and rhizosphere-associated microorganisms under long-term cultivation remains fragmentary. The research presented in our manuscript systematically studied response of Achnatherum inebrians infected by endophyte (Epichloe gansuensis) to long-term cultivation. Five-year field trials demonstrated that E. gansuensis endophyte significantly increased host plant coverage. It revealed that Epichloe endophyte-infected plants recruits beneficial Microvirga species involved in soil carbon and nitrogen cycles by exudating key metabolites (i.e., 5-Hydroxyindoleacetic acid) to help the host obtain nutrients, thereby promoting plant growth. Moreover, in vitro test experiments further demonstrated that key metabolite could enhance plant growth by promoting Microvirga enrichment.