Project Grant 20226701337080

** AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** NITROGEN (N OR N2), A LIMITING PLANT NUTRIENT RESULTING IN BENEFICIAL FERTILIZER APPLICATION TO CROPS, REQUIRES EXTENSIVE ENERGY TO PRODUCE INDUSTRIALLY AND HAS SEVERE ENVIRONMENTAL IMPACTS. CROP EVOLUTION HAS AFFECTED PLANT TRAITS THAT INFLUENCE AGROECOSYSTEM FUNCTION, SUCH AS NUTRIENT USE EFFICIENCY, AS WELL AS ASSOCIATIONS WITH BENEFICIAL ORGANISMS, SUCH AS MICROORGANISMS THAT FIX N2. MANY GRASSES CAN ASSOCIATE WITH ENDOPHYTIC AND FREE-LIVING MICROBES TO GAIN N. IN FACT, MAIZE (ZEA MAYS SSP. MAYS) FROM THE HIGHLANDS OF OAXACA, MEXICO, IS NOW KNOWN TO RECEIVE 25-80% OF ITS N FROM BACTERIA HARBORED IN MUCILAGE (OR GEL) COVERING AERIAL ROOTS ALONG THE STEM. TRAITS REQUIRED FOR THIS SYSTEM TO FUNCTION (E.G., AERIAL ROOT AND MUCILAGE PRODUCTION) AND N2 FIXATION HAVE BEEN OBSERVED IN WILD AND IMPROVED MAIZE TOO. THUS, VARIOUS FARMERS MAY ALREADY BE BENEFITING FROM THIS CAPACITY--AND OTHERS COULD BE. TO ENSURE THE PROMISE OF THIS TRAIT FOR SUSTAINABLE MAIZE PRODUCTION, WE MUST CLARIFY THEANCESTRAL NATURE OF N2 FIXATION IN ZEA AND DISCERN HOW THE CAPACITY TO FIX N2 VARIES ACROSS GENETIC RESOURCES REPRESENTATIVE OF THE DOMESTICATION, SPREAD, AND IMPROVEMENT OF MAIZE IN THE AMERICAS. MOREOVER, WE NEED TO BETTER UNDERSTAND THE IMPACT OF THIS N2 FIXATION ON AERIAL ROOTS ON PLANT PERFORMANCE. TO FILL THESE GAPS, WE PROPOSE TO USE FIELD EXPERIMENTS IN OHIO AND MEXICO THAT UNITE DIVERSE ZEA ACCESSIONS REPRESENTING STAGES OF CROP EVOLUTION: WILD, LANDRACE, HEIRLOOM, AND HYBRID VARIETIES. OUR EXPECTED OUTCOMES WILL ESTABLISH THE EVOLUTIONARY HISTORY AND IMPORTANCE OF N2 FIXATION IN ZEA--A TRAIT WITH GREAT POTENTIAL TO ENHANCE AGROECOSYSTEM FUNCTION GLOBALLY.