MASSIVE EFFORTS ARE UNDERWAY TO UNDERSTAND VARIATION IN ROOT TRAITS WITH THE GOAL OF SELECTING BENEFICIAL TRAITS THAT ENHANCE RESOURCE ACQUISITION AND PRODUCTIVITY FOR MEETING GLOBAL FOOD DEMANDS. THESE EFFORTS ARE USUALLY CONDUCTED WITHOUT INCLUDING BENEFICIAL ARBUSCULAR-MYCORRHIZAL FUNGAL (AMF) PARTNERSHIPS, A MUTUALISM BETWEEN AN ESTIMATED TWO-THIRDS OF HIGHER PLANTS AND FUNGI THAT ARE UBIQUITOUS IN THE ENVIRONMENT. INOCULATION WITH AMF HAS BEEN DEMONSTRATED TO SUBSTANTIALLY ENHANCE PLANT VIGOR IN AGRICULTURE AND RESTORATION. HOWEVER, RESULTS ARE OFTEN DIFFICULT TO REPLICATE DUE TO COMPLEX INTERACTIONS AMONG THE PLANT AND FUNGAL GENOTYPES AS WELL AS THE PLANT ASSOCIATED MICROBIOME. THE CONTEXT DEPENDENCE OF THESE INTERACTIONS IS A MAJOR FACTOR LIMITING EXPLOITATION OF AM FUNGI IN AGRICULTURE AND REMEDIATION, WHILE UNPREDICTABLE PLANT BENEFITS HINDER THE INCLUSION OF THESE FUNGI IN SCREENS FOR BENEFICIAL ROOT TRAITS. THIS RESEARCH WILL IDENTIFY FUNGAL, PLANT AND MICROBIOME TRAITS THAT PREDICT HOW PLANTS BENEFIT FROM THEIR AMF PARTNERS UNDER IMPORTANT ENVIRONMENTAL STRESSORS (SPECIFICALLY LOW NUTRIENT AVAILABILITY, DROUGHT, HIGH SALINITY, AND PATHOGEN INFECTION), WHICH WILL LEAD TO IMPROVED VARIETAL SELECTION AND PRODUCTIVITY GAINS, IN MARGINAL ENVIRONMENTS. WE ALSO PROPOSE A HIGHLY INNOVATIVE APPROACH TO DEVELOP SYNTHETIC BACTERIA COMMUNITIES (SYNCOMS) TO FACILITATE AMF COLONIZATION. WE WILL BUILD STATISTICAL EQUATION AND GENOME SCALE METABOLIC MODELS TO ADVANCE OUR CAPACITY TO PREDICT PLANT-MICROBIOME INTERACTIONS BY REVEALING FUNDAMENTAL LINKS BETWEEN ROOT TRAITS, INTRODUCED AMF, AND MICROBIAL GUILDS IN SOIL. BY DOING THIS WE WILL DEVELOP A FRAMEWORK TO PROVIDE TANGIBLE RECOMMENDATIONS FOR EXPLOITING THE BENEFITS THAT AMF PROVIDE TO PLANTS UNDER STRESS CONDITIONS.