Genomic Insights Into the Antifungal Activity and Plant Growth-Promoting Ability in Bacillus velezensis CMRP 4490

Abstract

The main objective of this study was to evaluate <i>Bacillus velezensis</i> strain CMRP 4490 regarding its ability to inhibit soil-borne plant pathogens and to increase plant growth. The study included evaluation of <i>in vitro</i> antifungal control, sequencing the bacterial genome, mining genes responsible for the synthesis of secondary metabolites, root colonization ability, and greenhouse studies for the assessment of plant growth-promoting ability. The strain was obtained from soil samples in the north of Paraná in Brazil and was classified as a <i>B. velezensis</i>, which is considered a promising biological control agent. <i>In vitro</i> assay showed that <i>B. velezensis</i> CMRP 4490 presented antagonistic activity against <i>Sclerotinia sclerotiorum</i>, <i>Macrophomina phaseolina</i>, <i>Botrytis cinerea</i>, and <i>Rhizoctonia solani</i> with a mycelial growth inhibition of approximately 60%, without any significant difference among them. To well understand this strain and to validate its effect on growth-promoting rhizobacteria, it was decided to explore its genetic content through genome sequencing, <i>in vitro</i>, and greenhouse studies. The genome of CMRP 4490 was estimated at 3,996,396 bp with a GC content of 46.4% and presents 4,042 coding DNA sequences. Biosynthetic gene clusters related to the synthesis of molecules with antifungal activity were found in the genome. Genes linked to the regulation/formation of biofilms, motility, and important properties for rhizospheric colonization were also found in the genome. Application of CMRP 4490 as a coating film on soybean increased from 55.5 to 64% on germination rates when compared to the control; no differences were observed among treatments for the maize germination. The results indicated that <i>B. velezensis</i> CMRP 4490 could be a potential biocontrol agent with plant growth-promoting ability.