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Endophytic bacteria occupy the same niche of phytopathogens and may produce metabolites that induce the host plant systemic resistance and growth. Host and environmental variables often determine the endophytic community’s structure and composition. In this study, we addressed whether the plant genotype, organ, and geographic location influence the structure, composition, and functionality of endophytic bacterial communities in Paullinia cupana . To characterize the communities and identify strains with potential application in agriculture, we analyzed two P. cupana genotypes cultivated in two cities of the State of Amazonas, Brazil. Endophytic bacteria were isolated from surface-disinfested root, leaf, and seed tissues through the fragmentation and maceration techniques. The colonization rate, number of bacteria, richness, diversity, and functional traits were determined. The plant growth-promoting ability of selected bacterial strains was assessed in Sorghum bicolor . We identified 95 bacterial species distributed in 29 genera and 3 phyla (Proteobacteria, Actinobacteria, and Firmicutes). The colonization rate, richness, diversity, and species composition varied across the plant organs; the last parameter also varied across the plant genotype and location. Some strains exhibited relevant plant growth-promoting traits and antagonistic traits against the main phytopathogens of P. cupana , but they were not separated by functional traits. The main bacterial strains with plant growth-promoting traits induced S. bicolor growth. Altogether, our findings open opportunities to study the application of isolated endophytic bacterial strains in the bioprospection of processes and products. [ABSTRACT FROM AUTHOR]

• Actinobacteria from P. cupana promote biological control of different phytopathogenic fungi. • S. griseocarneus R132 controls the development of anthracnose symptoms in pepper fruits and plants. • Streptomyces griseocarneus R132 promotes growth of the aerial part of Capsicum annuum plants. Endophytic actinomycetes are important for the prospection of biologically active compounds and the development of biotechnological processes in agriculture for the biological control of plant diseases and phytopathogens. Eleven endophytic actinobacteria species isolated from Paullinia cupana were screened for in vitro antibiosis against five phytopathogens and control of anthracnose in pepper (Capsicum annuum) fruits. Cultures of the most active actinobacteria were fractionated with methanol and ethyl acetate, and the anthracnose control capacity of the resulting extracts was evaluated. Actinobacteria-mediated growth promotion and control of root pathogens in pepper plants were evaluated in a greenhouse. Streptomyces griseocarneus R132 (i) inhibited the growth of phytopathogens the most strongly, ranging from 57.24 ± 4.54% (Fusarium oxysporum 46.7) to 73.93 ± 3.71% (Botryosphaeria dothidea CFMAC3); (ii) markedly controlled the development of anthracnose symptoms caused by Colletotrichum gloeosporioides MPU99 in pepper fruits and plants; and (iii) promoted growth of pepper plants, increasing 42% of shoot dry mass. Actinobacteria extracts effectively controlled the anthracnose symptoms and reduced the lesion size by 30% in pepper fruits. Streptomyces griseocarneus R132 is a promising tool for the biological control of both pre- and post-harvest plant pathogens and growth promotion in pepper. [ABSTRACT FROM AUTHOR]