| Congresso Brasileiro de Microbiologia 2023 | Resumo: 923-1 | ||||
Resumo:In 2021, the forestry sector accounted for 1.2% of the national GDP. The most utilized genus for timber production in Brazil is Eucalyptus, representing 75% of the total area of planted forests. In the pursuit of more sustainable alternatives that maintain productivity, the utilization of plant growth-promoting bacteria (PGPB) emerges as a promising tool for the forestry segment. With this objective, a bacterial consortium was tested on a large scale to evaluate its growth promotion effects on Eucalyptus seedlings. Additionally, the change in the endophytic bacterial composition of the seedlings following the introduction of the consortium was assessed. To achieve this, an inoculant consisting of five strains from the genera Paenibacillus, Paraburkholderia, Methylobacterium, Mesorhizobium, and Bacillus was introduced into the substrate and seedlings through immersion. The experimental design employed was factorial (3x2), with the first factor being the genotype of three commercial clones (X, Y, and Z) and the second factor being inoculation (with and without the use of the consortium). To observe the effectiveness of the colonization by the consortium strains and understand the endophytic bacterial composition, massive sequencing of the gene encoding the 16S rRNA subunit of the DNA extracted from the seedling roots was performed. To assess growth promotion and development, the length of the abovevground part was measured, and the mortality rate was evaluated. The results showed a change in the bacterial community structure in the samples that received the consortium compared to those that did not. The results obtained were highly dependent on the clone to which they were applied, despite showing high similarity among them. Inoculation influenced the abundance of the phylum Proteobacteria, reducing it, and increasing the abundance of the phylum Actinobacteria. Among the 409 genera found, the genus Ralstonia exhibited the highest average relative abundance in all treatments. Despite the inoculant's goal being to promote seedling growth, inoculation reduced the incidence of the genus Ralstonia, also exerting a biocontrol action, especially in clone Y. At the end of the experiment, only the genus Methylobacterium showed enrichment in clone Z. Inoculation also caused a significant alteration in the seedling quality frequency, resulting in reduced mortality in clone Y and increased seedlings in clone Z. The results obtained in this study can contribute to the understanding of the bacterial composition after inoculation and the improvement in the production of future consortia composed of PGPB for application in Eucalyptus seedlings. Palavras-chave: Endophytic bacteria, Consortium, Ralstonia, Inoculant, Bacterial composition Agência de fomento:Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPQ) | |||||