Production of DAPG and HCN by Pseudomonas sp. LBUM300 Contributes to the Biological Control of Bacterial Canker of Tomato

Abstract

Bacterial canker caused by Clavibacter michiganensis subsp. michiganensis is known to cause significant economic losses to tomato production worldwide. Biological control has been proposed as an alternative to current chemical containment methods, which are often inefficient and may leave adverse effects on the environment. However, only little headway has so far been made in developing biocontrol strategies against C. michiganensis subsp. michiganensis. To address this knowledge gap, we investigated the antagonistic capacity of PCA, produced by Pseudomonas sp. LBUM223, and DAPG and HCN, both produced by Pseudomonas sp. LBUM300, on C. michiganensis subsp. michiganensis under in vitro and in planta conditions. Nonsynthesizing isogenic mutants of the producer strains were also developed to further dissect the role of each individual metabolite on C. michiganensis subsp. michiganensis biological control. Novel specific quantitative polymerase chain reaction TaqMan assays allowed quantification of C. michiganensis subsp. michiganensis in tomato plants and rhizospheric soil. Pseudomonas spp. LBUM223 and LBUM300 significantly repressed C. michiganensis subsp. michiganensis growth in vitro, while their respective nonproducing mutants showed less or no significant antagonistic activity. In planta, only Pseudomonas sp. LBUM300 was capable of significantly reducing disease development and C. michiganensis subsp. michiganensis rhizospheric population, suggesting that the production of both DAPG and HCN was involved. In summary, simultaneous DAPG/HCN production by Pseudomonas sp. LBUM300 shows great potential for controlling bacterial canker of tomato.

Interaction between 2,4-Diacetylphloroglucinol- and Hydrogen Cyanide-Producing Pseudomonas brassicacearum LBUM300 and Clavibacter michiganensis subsp. michiganensis in the Tomato Rhizosphere

“…The symptoms observed on the plants inoculated with C. michiganensis subsp. michiganensis were similar to those reported previously (18).…”

“…michiganensis spreads through the xylem vessels, eventually colonizing the whole plant and causing systemic infection, which leads to unilateral wilting of leaves, development of canker lesions, tissue disintegration, and plant death (17). We previously reported (18) that under in planta conditions, development of bacterial canker disease in tomato was reduced by inoculation with Pseudomonas brassicacearum LBUM300, which is able to produce both DAPG and HCN (19), but not by inoculation with its phlD-or hcnC-deficient isogenic mutant counterparts. This suggests that the production of both antimicrobial metabolites contributes to reducing disease development and that P. brassicacearum LBUM300 may have the potential to be used as a biocontrol agent for bacterial canker.…”

“…michiganensis (18), it remains unknown how the capacity to produce DAPG and HCN in the absence/presence of C. michiganensis subsp. michiganensis might impact rhizosphere colonization by P. brassicacearum LBUM300.…”

Biofertilising, plant-stimulating and biocontrol potentials of maize plant growth promoting rhizobacteria isolated in central and northern Benin

“…HCN production is a common activity in Bacillus (50%) in rhizosphere soils (Ahmad et al, 2008). Pseudomonas strains producing HCN are used in biological control against bacterial canker of tomato (Lanteigne et al, 2012). HCN production by the P. fluorescens CHA0 strain reduces the pathogenicity of fungi such as Thielaviopsis basicola, a black rot agent in tobacco (Mercado-Blanco and Bakker, 2007).…”

Plant Growth Promoting Rhizobacteria (PGPR): A Bioprotectant bioinoculant for Sustainable Agrobiology. A Review

“…Its cyanide ion inhibits most metalloenzymes, especially copper containing cytochrome c oxidases (Blumer and Haas 2000). Cyanide produced by Pseudomonas strains has successfully been used to curb canker of tomato (Lanteigne et al, 2012).As a secondary metabolite produced by gram negative bacteria, it is formed from glycine and catalyzed by HCN synthase (Castric, 1994). P. fuorescens strain CHA0 (Voisard et al, 1989) was used to control tobacco black root rot caused by Thielaviopsis basicola (Laville et al, 1998).…”