Caracterização baseada em genômica evidencia o potencial de bactérias endofíticas para promoção do crescimento de plantas

Abstract

Endophytic microorganisms have received notoriety for their potential as promoters of plant development, even under stress conditions. Because of it, there is an increasing interest in the practical applications of these microorganisms for sustainable agriculture, cultivation in saline soils and restoration of areas degraded by organic pollutants and heavy metals. For it to be possible, in addition to proving the beneficial effects on plants, biosafety studies are necessary to ensure that endophytes are not pathogenic or produce toxins with a cytotoxic effect, which therefore, would be safe for the entire ecosystem. The characterization of the beneficial effects of microorganisms on plants can be done through phenotypic studies. However, genomic analysis can also be applied in the characterization as a complementary tool for searching for potential features of interest. This study sought to analyze the genome of six bacteria isolated from corn plants: Ochrobactrum sp. CNPMS2088, Bacillus megaterium UFMG50, Klebsiella pneumoniae UFMG51, Pantoea ananatis UFMG54, Microbacterium sp. UFMG61 and Pseudomonas putida UFMG81. These bacteria were investigated in order to explore the genomic potential and compare it to the previous results from in vitro and in vivo experiments. The genomics functions investigated are related to: plant growth promotion; ability to colonize plant tissues; potential to control phytopathogenic agents; physiological and metabolic versatility, which is a characteristic that can favor adaptability of these bacteria to environmental variations; virulence and drug resistance, which is an important assessment for biosafety. The results of the genomic analysis reinforce the potential of using the bacteria studied as bioinoculants already observed in the previous in vivo and in vitro experiments. The bacteria stood out in the genomic and phenotype studies in characteristics such as: phosphorus solubilization, production of phytohormones and production of siderophores. Considering the genomic analysis, K. pneumoniae UFMG51 was the bacteria which had the largest number of CDS associated with features of interest in plant growth promotion such as nitrogen fixation and P metabolism, in addition to demonstrating potential for bioremediation due to the total number of CDS associated to the degradation of aromatic compounds and resistance to heavy metals. Hence, genomic analysis allowed to explore the potential of bacteria for a larger variety of features of interest which have not yet been tested in the laboratory. This type of analysis is an important tool to guide future work to design phenotypic tests to proof whether these microrganisms are effective in characteristics of interest to be applied as bioinoculants.