** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** SUMMARYCLIMATE CHANGE IS PREDICTED TO INCREASE THE VARIABILITY IN TIMING AND AMOUNT OF PRECIPITATIONACROSS THE GLOBE, AND STRATEGIES TO MITIGATE THE NEGATIVE IMPACTS ARE NECESSARY. COMPONENTS OFTHE PLANT MICROBIOME ARE CAPABLE OF ENHANCING DROUGHT TOLERANCE IN AGRICULTURAL AND RANGELANDCOMMUNITIES AND COULD SUSTAIN ECOSYSTEM FUNCTION AND AGRICULTURAL YIELDS IN THE FACE OF CLIMATECHANGE. ARBUSCULAR MYCORRHIZAL FUNGI ARE BENEFICIAL PLANT SYMBIONTS KNOWN TO PROMOTEDROUGHT TOLERANCE. WE PROPOSE TO LEVERAGE THE INTERNATIONAL COLLECTION OF (VESICULAR-)ARBUSCULAR MYCORRHIZAL FUNGI (INVAM), OUR LAB CULTURE COLLECTION, AND AM FUNGAL SEQUENCEDATA FROM ACROSS PRECIPITATION GRADIENTS TO SELECT AM FUNGAL ISOLATES THAT ARE LIKELY TO BERESISTANT TO DROUGHT AND CONFER DROUGHT TOLERANCE TO ASSOCIATED HOST PLANT SPECIES.THE GEOGRAPHIC ORIGIN OF AM FUNGAL ACCESSIONS IN INVAM SPAN THE GLOBE. EACH OF THEAPPROXIMATELY 1000 ISOLATES ARE CHARACTERIZED BY THEIR SPORE MORPHOLOGY AND HYPHALCHARACTERISTICS. IN ADDITION, OUR LAB HAS ADDITIONAL AMF THAT WE HAVE ISOLATED FROM INDIANA,ILLINOIS, MISSOURI, KANSAS AND OKLAHOMA. WE WILL USE PHYLOGENETIC AND MORPHOLOGICAL TRAITS,AND GEOGRAPHIC ORIGIN, TO IDENTIFY AND PREDICT WHICH AMF SPECIES OR ISOLATES ARE MOSTPROFICIENT AT CONFERRING DROUGHT TOLERANCE TO THEIR PLANT HOSTS. USING THESE DATA AND AMPLICONDATASETS OF AMF ACROSS NATURAL MOISTURE GRADIENTS AND EXPERIMENTAL MANIPULATIONS OFPRECIPITATION IN THE MIDWESTERN USA, WE WILL IDENTIFY AM FUNGAL CANDIDATES FOR TESTING. WE WILLTHEN ESTABLISH GREENHOUSE EXPERIMENTS TO TEST THEIR ABILITY TO INCREASE DROUGHT TOLERANCE ONSORGHUM (SORGHUM BICOLOR) AND BIG BLUESTEM (ANDROPOGON GERARDII).WE WILL MEASURE THE ABILITY OF AMF TO CONFER DROUGHT TOLERANCE THROUGH GROWTH,ASSIMILATION AND STOMATAL CONDUCTANCE RESPONSE TO DROUGHT. WE WILL THEN EVALUATE WHETHER THESEMETRICS ARE BEST PREDICTED BY FUNGAL TRAITS, ISOLATE ORIGIN, OR INFORMATION ON DISTRIBUTION. THE BESTFUNGAL ISOLATES WILL BE USED IN FIELD TESTS OF DROUGHT RESILIENCE IN FUTURE TRIALS. THIS RESEARCHADVANCES EFFORTS OF BEST UTILIZE PLANT MICROBIOMES.