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Introduction: The extensive use of chemical fertilizers has served as a response to the increasing need for crop production in recent decades. While it addresses the demand for food, it has resulted in a decline in crop productivity and a heightened negative environmental impact. In contrast, plant probiotic bacteria (PPB) offer a promising alternative to mitigate the negative consequences of chemical fertilizers. PPB can enhance nutrient availability, promote plant growth, and improve nutrient uptake efficiency, thereby reducing the reliance on chemical fertilizers. Methods: This study aimed to evaluate the impact of native Rhizobium strains, specifically Rhizobium calliandrae LBP2-1, Rhizobium mayense NSJP1-1, and Rhizobium jaguaris SJP1- 2, on the growth, quality, and rhizobacterial community of tomato crops. Various mechanisms promoting plant growth were investigated, including phosphate solubilization, siderophore production, indole acetic acid synthesis, and cellulose and cellulase production. Additionally, the study involved the assessment of biofilm formation and root colonization by GFP-tagged strains, conducted a microcosm experiment, and analyzed the microbial community using metagenomics of rhizospheric soil. Results: The results showed that the rhizobial strains LBP2-1, NSJP1-1 and SJP1-2 had the ability to solubilize dicalcium phosphate, produce siderophores, synthesize indole acetic acid, cellulose production, biofilm production, and root colonization. Inoculation of tomato plants with native Rhizobium strains influenced growth, fruit quality, and plant microbiome composition. Metagenomic analysis showed increased Proteobacteria abundance and altered alpha diversity indices, indicating changes in rhizospheric bacterial community. Discussion: Our findings demonstrate the potential that native Rhizobium strains have to be used as a plant probiotic in agricultural crops for the generation of safe food and high nutritional value.
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Background: The whole-genome sequences of nine Rhizobium species were evaluated using different in silico molecular techniques such as AFLP-PCR, restriction digest, and AMPylating enzymes. The entire genome sequences were aligned with progressiveMauve and visualized by reconstructing phylogenetic tree using NTSYS pc 2.11X. The "insilico.ehu.es" was used to carry out in silico AFLP-PCR and in silico restriction digest of the selected genomes. Post-translational modification (PTM) and AMPylating enzyme diversity between the proteome of Rhizobium species were determined by novPTMenzy. Results: Slight variations were observed in the phylogeny based on AFLP-PCR and PFGE and the tree based on whole genome. Results clearly demonstrated the presence of PTMs, i.e., AMPylation with the GS-ATasE (GlnE), Hydroxylation, Sulfation with their domain, and Deamidation with their specific domains (AMPylating enzymes) GS-ATasE (GlnE), Fic, and Doc (Phosphorylation); Asparagine_hydroxylase and Collagen_prolyl_lysyl_hydroxylase; Sulfotransferase; and CNF (Cytotoxic Necrotizing Factors), respectively. The results pertaining to PTMs are discussed with regard to functional diversities reported in these species. Conclusions: The phylogenetic tree based on AFLP-PCR was slightly different from restriction endonuclease- and PFGE-based trees. Different PTMs were observed in the Rhizobium species, and the most prevailing type of PTM was AMPylation with the domain GS-ATasE (GlnE). Another type of PTM was also observed, i.e., Hydroxylation and Sulfation, with the domains Asparagine_hydroxylase and Collagen_prolyl_lysyl_hydroxylase and Sulfotransferase, respectively. The deamidation type of PTM was present only in Rhizobium sp. NGR234. How to cite: Qureshi MA, Pervez MT, Babar ME, et al. Genomic comparisons of Rhizobium species using in silico AFLP-PCR, endonuclease restrictions and ampylating enzymes.