Soil microorganisms, including arbuscular mycorrhizal fungi (AMF), one of the most widespread and functionally important symbioses on earth, have enormous potential for promoting sustainable agriculture and food security. However, the mass production of a safe and robust inoculum, produced in vitro at an affordable cost, remains difficult. The EU-funded MycUpscaling project will address this challenge and determine the genes responsible for increasing triacylglycerol (TAG) accumulation in the symbiotic interface and for increasing spore numbers to create high-quality, cost-effective AMF inoculants for application in agroecosystems. The project will include combinatorial lipid metabolic engineering, selection of mycorrhized TAG-accumulating hosts, in vitro and in vivo lipid flux analysis and in vitro spore domestication. This target required a multi-disciplinary research activity, combining materials science, and specific equipment. Such an approach was possible by merging competences of the two international experts involved in the project and making use of laboratory facilities available at the two hosting Organizations.