Uncovering wheat growth promotion traits by inspecting PGPB genomes

TORRES-MANNO, MARIANO; GIZZI, FERNÁN OSCAR; BLANCATO, VICTOR; DAURELIO, LUCAS D.; ESPARIZ, MARTÍN

Congreso; Congreso Argentino de Bioinformática y Biología Computacional; 2021

Background:Wheat is one of the principal cereals of Argentine agriculture and its cultivation is considered strategic inrotations due to its contribution to the sustainability of the soils. Multiple factors can affect the wheatproduction generating considerable losses in its yield. Plant growth promoting bacteria (PGPB) cancolonize the rhizospheres of plants, and act as biofertilizers and antagonists of pathogens (biopesticides).Due to this, they emerged as a technological alternative for a sustainable agricultural exploitation, as areplacement for agrochemicals. Many of these microorganisms belong to the genus Bacillus and proliferatein soils exploited agriculturally and its mechanism are yet to be uncover.Results:In this work we characterize six wheat associated strains presenting PGPB and biocontrol propertiesbelonging to Bacillus velezensis and Priestia megaterium (formerly known as Bacillus megaterium). Thewhole genome sequences were determined using Illumina and PacBio technology. The taxonomy identitywas defined comparing available genomes from 478 B. velezensis and 113 P. megaterium group. The 591available strains along with the 6 isolated were complete reclassified using Multiple Locus SequencesAnalysis (MLSA) and Average Nucleotide Identity (ANI). A comparative genomic analysis was processedin order to identify the plant growth promoting mechanism of these strains. Known secondary metaboliteand general PGP pathways were searched first using the GeM-Pro algorithm. This pathway search upon thesix strains and available genomes exposes some of the possible mechanisms in growth promoting andbiocontrol. Additional potential pathways were searched using the antiSMASH platform resulting inpotential new pathways for P. megaterium and B. velezensis isolated strains. Another comparative genomicanalysis with these new pathways was performed with the available genomes with the aim of finding theexclusive genes that correspond with the differential plant growth promoting phenotypes. As result, wefound exclusive pathways in the P. megaterium strains involving Non-Ribosomal Peptide Synthases(NRPS) and Polyketide Synthase (PKS) that were not detected in the non-redundant nucleotide GenBankdatabase. Secondly, thanks to the PacBio technology, we confirm that these gene clusters are coded in twodifferent plasmids. Furthermore, a rare NRPS pathway were found in the two B. velezensis strains that werenot common in the analyzed genomes from B. velezensis group.Conclusions:The results show that there are 33% misclassified strains of B. velezensis group when using completegenome tools. This implies the necessity of a framework for true genomoespecies classification. The newpathways found in the isolated strains may suggest that these are recently acquired gene clusters as resultof adaptation to the environment.