Whole Genome Sequence of Bacillus velezensis Strain GUMT319: A Potential Biocontrol Agent Against Tobacco Black Shank Disease

Abstract

Phytophthora nicotianae causes black shank, a serious soil-borne disease, in tobacco. In this study, the Bacillus strain GUMT319 was isolated from the rhizosphere of healthy tobacco plants grown in a field in Guizhou with a high incidence of tobacco black shank. Genome sequencing revealed that GUMT319 contained a single circular chromosome 3,940,023 bp in length, with 4,053 predicted genes and an average GC content of 46.6%. Based on phylogenomic analyses, GUMT319 was designated as Bacillus velezensis. The genome of GUMT319 contained more than 60 genes and 13 gene clusters that have previously been found to be active in antifungal mechanisms, biofilm formation, and chemotaxis motility. Additionally, confocal laser scanning microscopy and scanning electron microscopy showed that GUMT319 formed a spatially organized biofilm in vivo. In addition, lauric acid negatively regulated biofilm formation. This is the first study to report that nicotine in tobacco root exudates was a chemoattractant for biocontrol Bacillus strains. In this study, we identified new interactions between beneficial microorganisms and tobacco roots in the rhizosphere. Moreover, dual culture tests in vitro showed that GUMT319 inhibited the growth of P. nicotianae and also displayed inhibitory effects against eight other plant pathogens, namely, Colletotrichum scovillei, Colletotrichum capsici, Fusarium carminascens, Sclerotinia sclerotiorum, Alternaria alternata, Phomopsis sp., Phyllosticta sorghina, and Exserohilum turcicum. Furthermore, GUMT319 exhibited > 70% control efficiency against tobacco black shank in field experiments conducted in 2018–2020. Thus, GUMT319 was more effective in controlling the incidence of tobacco black shank than other treatments including fungicide application. Overall, these results suggested that GUMT319 (B. velezensis) could be used as a potential biocontrol agent against tobacco black shank.

Biocontrol Ability of the Bacillus amyloliquefaciens Group, B. amyloliquefaciens, B. velezensis, B. nakamurai, and B. siamensis, for the Management of Fungal Postharvest Diseases: A Review

“…In general, there is a lack of information regarding population dynamics to explain bacterial behavior in the plant host. In agreement with this conclusion, some reports have indicated that Bacillus biocontrol strains do not show high consistency in the field because they are not able to colonize successfully different plants and the colonization ability is dependent on the environmental conditions. , …”

“…In agreement with this conclusion, some reports have indicated that Bacillus biocontrol strains do not show high consistency in the field because they are not able to colonize successfully different plants and the colonization ability is dependent on the environmental conditions. 14,16 Regarding the advances in the elucidation of the factors involved in the colonization ability of B. amyloliquefaciens species, Fedele et al studied the colonization ability of commercial strains B. amyloliquefaciens QST713, D747, and FZB24 in grapes, observing the highest number of cells at 25 °C and 100% humidity. 48 Liu et al indicated that γpolyglutamic acid (γ-PGA) promoted the colonization ability of B. amyloliquefaciens C06 in stone fruits.…”

“…One of the most common alternative strategies to overcome these limitations is using bacterial biocontrol agents. , In this regard, Bacillus species have been thoroughly studied for the control of postharvest fungal diseases. − Bacillus is a ubiquitous environmental Gram-positive bacterium that is commonly associated with plants and the rhizosphere . Numerous Bacillus strains produce volatile organic compounds (VOCs) and cyclic lipopeptides with strong antifungal activities. − Recent reports have indicated that dipicolinic acid (DPA), one of the major components of Bacillus spores, also plays an important role in its antifungal properties. , In addition, it has been reported that several Bacillus strains induce disease resistance in postharvest products against pathogen infection by enhancing the activity of defense-related proteins …”

Bacillus velezensis Strain GUMT319 Reshapes Soil Microbiome Biodiversity and Increases Grape Yields

“…The Bacillus velezensis strain GUMT319 rhizobacteria was originally isolated from the rhizosphere of field-grown tobacco plants in Guizhou with a high incidence of tobacco black shank. Previous studies confirmed that GUMT319 is a useful biocontrol agent [28]. We treated the Vitis vinifera L. variety 'Sweet Sapphire' with GUMT319 by root irrigation to determine its impact on grape plant growth.…”

“…Application of PGPR can help maintain sustainable agricultural development [ 8 , 24 , 25 , 26 , 27 ]. B. velezensis strain GUMT319 is a PGPR rhizobacteria isolated from Guizhou province [ 28 ]. In this study, we treated vineyard soils with GUMT319 to determine the effects of GUMT319 on grape yield and found that GUMT319 can function like a PGPR.…”