This is the final version of the article. Available from Wiley via the DOI in this record.Intensive agriculture, which depends on unsustainable levels of agrochemical inputs, is environmentally harmful, and the expansion of these practices to meet future needs is not economically feasible. Other options should be considered to meet the global food security challenge. The plant microbiome has been linked to improved plant productivity and, in this microreview, we consider the endosphere – a subdivision of the plant microbiome. We suggest a new definition of microbial endophyte status, the need for synergy between fungal and bacterial endophyte research efforts, as well as potential strategies for endophyte application to agricultural systems.Rothamsted Research receives strategic funding from the Biotechnology and Biological Sciences Research Council (BBSRC), and we acknowledge funding from the BBSRC Institute Strategic Programme Grant (ISPG), ‘Optimization of nutrients in soil–plant systems’ (BBS/E/C/0005196)
