Biocontrole de Fusarium verticillioides em milho e sorgo com bactérias dos gêneros Bacillus, Paenibacillus e Pseudomonas

Abstract

Bacteria from the genera Bacillus, Paenibacillus, and Pseudomonas are widely recognized as potential biological control agents. They suppress pathogens, induce systemic resistance, and promote plant growth through the production of lipopeptide, enzymes, volatile organic compounds (VOCs), and phytohormones. Fusarium verticillioides is known as the etiological agent of stalk and ear rot in crops such as maize and sorghum. This study aimed to elucidate the mechanisms employed by selected bacterial strains as biological control agents, focusing on both direct interactions, such as VOC-mediated antagonism, and indirect interactions involving induction of systemic resistance in host plants. The first chapter presents a comprehensive literature review on plant-microbe interactions, emphasizing biological control mechanisms and the pathogenicity of F. verticillioides to provide context and theoretical foundation for the work. The second chapter investigates the effects of VOCs emitted by Bacillus, Paenibacillus, and Pseudomonas strains on the mycelial growth of F. verticillioides in vitro, as well as their influence on the growth of Arabidopsis thaliana. Significant fungal growth inhibition and stimulation of plant development were observed, alongside volatilome profiling of the bacterial strains. The third chapter evaluates the capacity of B. velezensis CNPMS-22 and P. ottowii LIS04 to promote growth and induce defense responses in maize and sorghum seedlings under both pathogen co-inoculation and separated hydroponic systems, through expression analysis of defense- and growth-related marker genes. The fourth chapter details the genome sequencing and comparative genomic analysis of P. ottowii LIS03, revealing high genomic plasticity, the presence of unique genes, and an extensive repertoire of gene clusters for the biosynthesis of secondary metabolites, such as siderophores, polyketides, and antimicrobials. Overall, the results broaden the understanding of the multifactorial mechanisms involved in the biological control of F. verticillioides and provide scientific and genomic foundations for the development of more efficient and sustainable bioinputs for agriculture.