Diversity and plant growth-promoting traits of endophytic bacteria isolated from maize cropped in organic and low-input agricultural systems in southern Brazil

Plant growth-promoting bacteria (PGPB) may enhance plant growth and health through several mechanisms, contributing for sustainable agriculture. We isolated and characterized endophytic bacteria from stems of landrace maize (Zea mays L.) grown under low-input and organic systems in southern Brazil. The 16S rRNA analysis revealed 83 isolates within 14 genera, including α-Proteobacteria, β-Proteobacteria, γ-Proteobacteria, Actinomycetia, and Bacilli classes. The synthesis of indolic compounds was widespread among the strains, as well as the enhancement of N concentration in N-free media, a putative capacity for biological nitrogen fixation. Phosphate solubilization prevailed in Burkholderia and Paraburkholderia strains, while siderophores production was observed in all genera, except Microbacterium. Inoculation with selected strains confirmed growth-promotion on maize plantlets, particularly Sphingomonas sp. CNPSo 2378 and Bacillus velezensis CNPSo 2384, whose genomes were sequenced and revealed PGPB features and evolutionary relationships, shedding light on the diversity, functional traits, and occurrence in low-input and organic agricultural systems. Data summary The 16S rRNA gene sequences have been deposited in the NCBI GenBank database, with accession numbers provided in supplementary material (Table S1). The genomic sequences have also been deposited in the GenBank database, with the following accession numbers: JAXCMJ000000000 for CNPSo 2378 and JAXCMK000000000 for CNPSo 2384. Raw data on the effects of bacterial isolates on the plant growth-promoting of maize plantlets are available at figshare database, with the following DOI: 10.6084/m9.figshare.27610290.