MUCH OF THE UNITED STATES AGRICULTURAL SYSTEM RELIES ON BREEDING DESIRABLE TRAITS THAT INCLUDE HIGH YIELD, DISEASE SUPPRESSION, AND DROUGHT TOLERANCE, AMONG OTHERS. ONE OF THE CONSTRAINTS OF RELYING ON BREEDING TECHNIQUES TO IMPROVE CROP TRAITS IS THE ISSUE OF TIME. FOR MOST BREEDING PROGRAMS, ONE SELECTION CYCLE OCCURS ANNUALLY, WHICH MEANS THAT WE HAVE ONLY 35 BREEDING CYCLES UNTIL 2050--A CRITICAL GLOBAL TIME POINT THAT CENTERS ON THE QUESTION OF HOW TO FEED OVER 9 BILLION PEOPLE. IT IS UNLIKELY THAT BREEDING ALONE WILL PROVIDE THE SOLUTIONS TO INCREASE YIELDS FOR SUSTAINING HUMAN POPULATION GROWTH, WHILE ALSO RESPONDING TO CHANGES IN CLIMATE. OUR RESEARCH PROJECT ADDRESSES THIS CONCERN BY INITIATING RESEARCH THAT FOCUSES ON ASSEMBLING COLLECTIONS OF SOIL MICROBIOTA--BACTERIA, FUNGI, AND VIRUSES--THAT ALTOGETHER, REINFORCE DESIRABLE CROP TRAITS. IN ESSENCE, WE ARE "BREEDING" GROUPS OF PLANT-ASSOCIATED MICROBIOTA THAT ARE ABLE TO ENHANCE PLANT YIELD BY ENRICHING PLANT ROOT ZONES WITH BENEFICIAL MICROORGANISMS. AT PRESENT, MANY TOP AGRIBUSINESS COMPANIES, INCLUDING MONSANTO, SYNGENTA, DUPONT, AND BASF, ARE INVESTING IN MICROBIAL-BASED METHODS THAT INFLUENCE CROP TRAITS. INDUSTRY IS RELYING PRIMARILY ON A SINGLE SPECIES OR STRAIN OF MICROORGANISM AS AN INOCULANT IN PLANT SEEDS OR DIRECTLY INTO SOILS. OUR APPROACH DIFFERS IN THAT IT INCLUDES COMPLEX COMMUNITIES OF MICROORGANISMS THAT ARE ASSEMBLED THROUGH REPEATED SELECTIONS ON THE PLANT HOST TRAIT, SUCH AS BIOMASS OR SEED YIELD. THE SHORT LIFECYCLE OF BACTERIA AND THEIR ABILITY TO SHIFT POPULATION STRUCTURE RAPIDLY, IN RESPONSE TO SELECTION, FACILITATES THE BREEDING OF SOIL MICROBIOTA FOR PLANT PRODUCTION SYSTEMS.BY 2050, THE HUMAN POPULATION IS EXPECTED TO REACH OVER 9 BILLION PEOPLE, WITH THE MAJORITY CONCENTRATED IN AFRICA, SOUTHERN ASIA, AND EASTERN ASIA. FOR PARTS OF THESE SECTIONS OF THE WORLD, IT IS CHALLENGING TO DEVELOP INTENSIVE AGRICULTURAL SYSTEMS ROUTINELY USING INDUSTRIAL AMMONIA FERTILIZERS TO SUSTAIN HIGH YIELDS. SYNTHETIC FERTILIZERS (BASED ON THE HABER-BOSCH PROCESS) CONSUME HIGH AMOUNTS OF FOSSIL FUEL ENERGY IN THEIR MANUFACTURE AND CONTRIBUTE TO CHRONIC NONPOINT SOURCE POLLUTION IN HOTSPOTS OF AGRICULTURAL PRODUCTION, SUCH AS FOUND IN THE SALINAS VALLEY AREA OF CALIFORNIA. DEVELOPING A PLANT MICROBIOME FOCUS TO INTERNATIONAL CROP PRODUCTION WILL HELP PROMOTE SUSTAINED YIELDS IN MAJOR PARTS OF THE WORLD LACKING THE CAPACITY FOR INDUSTRIAL-BASED AGRICULTURE, IN ADDITION TO MAINTAINING CROP PRODUCTIVITY IN THE U.S. MANY CROPPING SYSTEMS ALREADY INCLUDE A FOCUS ON THE MICROBIOME FOR IMPROVED NUTRIENT MANAGEMENT; THESE INCLUDE RHIZOBIA FOR LEGUMES AND SEVERAL ARBUSCULAR MYCORRHIZAL FUNGI (AMF) FOR CEREAL CROPS. HOWEVER, PLANTS THAT DO NOT FORM ASSOCIATIONS WITH SYMBIONTS RELY HEAVILY ON FERTILIZER ADDITIONS. BRASSICA CROP PRODUCTION (MANY CULTIVARS OF WHICH SERVE AS THE GREEN VEGETABLE STAPLE OF MANY POPULATIONS IN DEVELOPING COUNTRIES) WOULD BENEFIT HEAVILY FROM GREATER NITROGENMANAGEMENT VIA SOIL BIOTIC MANIPULATIONS, AND SERVE AS A MODEL FOR ADDITIONAL CROPS THAT DO NOT FORM SYMBIOTIC RELATIONSHIPS.THE PROPOSED RESEARCH WILL INCLUDE SEQUENCING OF THE MICROBIOMES IN AN EFFORT TO IDENTIFY WHO COMPRISES THE MICROBIOMES THAT ARE ASSOCIATED WITH AN ENHANCED SEED YIELD PHENOTYPE AND CORRESPONDING HIGH NITROGEN CAPTURE TRAITS. WE WILL BE USING 16S AND 18S BAR-CODED PAIRED-END READS FOR CHARACTERIZATION OF THE SOIL MICROBIOME USING THE ILLUMINA HISEQ PLATFORM. THE SEQUENCING METHODS WILL ALLOW US TO ASSESS HOW THE MICROBIOMES CHANGE IN COMMUNITY COMPOSITION OVER GENERATIONS OF SELECTION, IN RELATION TO THE DEVELOPMENT OF HIGHER SEED YIELD IN THE HOST PLANTS. FUNCTIONAL ANALYSIS USING PLANT RNA-SEQ, SOIL EXTRACELLULAR ENZYME ACTIVITY, PLANT TISSUE 15N ENRICHMENT, AND NITROGEN MINERALIZATION WILL HELP EXPLAIN HOW THE MICROBIOMES ARE MODIFYING PLANT PHENOTYPES VIA PLANT GENE EXPRESSION AND COORDINATED RESOURCE GAIN. THESE FUNDAMENTAL INVESTIGATIONS INTO THE INTERACTIONS OF PLANTS AND THEIR ASSOCIATED MICROBIOTA WILL HELP PAVE THE WAY FOR MICROBIOME-ENHANCEMENT OF AGRICULTURAL PRODUCTION SYSTEMS.