**AWARDS ISSUED PRIOR TO JANUARY 20, 2025, WERE FUNDED UNDER PREVIOUS ADMINISTRATIONS AND MAY NOT REFLECT THE PRIORITIES AND POLICIES OF THE CURRENT ADMINISTRATION.** BENEFICIAL MICROORGANISMS, SUCH AS PLANT GROWTH-PROMOTING RHIZOBACTERIA (PGPR) STIMULATE PLANT GROWTH AND OFTEN ENHANCE DEFENSES AGAINST PATHOGENS AND INSECT PESTS VIA INDUCED SYSTEMIC RESISTANCE (ISR), MAKING THEM IDEAL CANDIDATES FOR INTEGRATION IN SUSTAINABLE PEST MANAGEMENT STRATEGIES. HOWEVER, THE COMPLEX REGULATORY MECHANISMS INVOLVED IN PGPR-MEDIATED PLANT-INSECT INTERACTIONS ARE POORLY UNDERSTOOD. THE OVERARCHING GOAL OF THIS PROJECT IS TO IMPROVE OUR UNDERSTANDING OF THE MOLECULAR MECHANISMS BY WHICH PGPR PROTECT PLANTS AGAINST INSECT DAMAGE. THE STUDY WILL USE AS RESEARCH SYSTEMS TWO ECONOMICALLY IMPORTANT CROPS, COTTON AND MAIZE, AND THEIR MAJOR INSECT PESTS, BEET ARMYWORM (SPODOPTERA EXIGUA) AND FALL ARMYWORM (SPODOPTERA FRUGIPERDA), RESPECTIVELY. OUR CENTRAL HYPOTHESIS IS THAT APPLICATION OF PGPR TO PLANTS WILL RESULT IN INCREASED PRODUCTION OF XYLEM-RESIDENT ISR SIGNALS, DEFENSIVE METABOLITES, AND UPREGULATION OF DEFENSE-RELATED GENES RESULTING IN INCREASED RESISTANCE TOINSECT PESTS. THE PROJECT HAS THREE OBJECTIVES: 1) IDENTIFY PGPR BLENDS THAT ELICIT STRONG ISR AGAINST KEY INSECT PESTS OF COTTON AND MAIZE, 2) UNCOVER BIOCHEMICAL AND MOLECULAR MECHANISMS OF PGPR-MEDIATED ISR, AND 3) DETERMINE ECOLOGICAL RAMIFICATIONS OF PGPR TREATMENT ON ARTHROPOD COMMUNITY. USING AN INTEGRATED APPROACH INVOLVING BIOLOGICAL AND MOLECULAR TECHNIQUES COUPLED WITH FIELD STUDIES, THIS STUDY WILL EXPAND OUR UNDERSTANDING OF HOW PLANTS INTEGRATE SIGNALS FROM BENEFICIAL MICROBES AND INSECTS INTO ADAPTIVE RESPONSES TO COPE WITH BIOTIC STRESS. THE KNOWLEDGE GAINED WILL INFORM DEVELOPMENT OF SUSTAINABLE MANAGEMENT PRACTICES TO PROMOTE PLANT HEALTH AND PRODUCTIVITY.