Interplay between orfamides, sessilins and phenazines in the control of Rhizoctonia diseases by Pseudomonas sp. CMR12a

Abstract

We investigated the role of phenazines and cyclic lipopeptides (CLPs) (orfamides and sessilins), antagonistic metabolites produced by Pseudomonas sp. CMR12a, in the biological control of damping-off disease on Chinese cabbage (Brassica chinensis) caused by Rhizoctonia solani AG 2-1 and root rot disease on bean (Phaseolus vulgaris L.) caused by R. solani AG 4-HGI. A Pseudomonas mutant that only produced phenazines suppressed damping-off disease on Chinese cabbage to the same extent as CMR12a, while its efficacy to reduce root rot on bean was strongly impaired. In both pathosystems, the phenazine mutant that produced both CLPs was equally effective, but mutants that produced only one CLP lost biocontrol activity. In vitro microscopic assays revealed that mutants that only produced sessilins or orfamides inhibited mycelial growth of R. solani when applied together, while they were ineffective on their own. Phenazine-1-carboxamide suppressed mycelial growth of R. solani AG 2-1 but had no effect on AG 4-HGI. Orfamide B suppressed mycelial growth of both R. solani anastomosis groups in a dose-dependent way. Our results point to an additive interaction between both CLPs. Moreover, phenazines alone are sufficient to suppress Rhizoctonia disease on Chinese cabbage, while they need to work in tandem with the CLPs on bean.

Characterization of Toxin Complex Gene Clusters and Insect Toxicity of Bacteria Representing Four Subgroups of Pseudomonas fluorescens

“…Rhizoxin is a 16-member macrolide that binds to β-tubulin, thereby interfering with microtubule dynamics during mitosis, and is toxic to many eukaryotes [41]. Orfamide A is a cyclic lipopeptide with surfactant properties that aids in bacterial motility across surfaces and solubilization of certain substrates [42], inhibition of some oomycetes and fungi [42,43,44], and toxicity to the green peach aphid [45]. Chitinases can degrade the peritrophic membrane, a chitin-based matrix in the insect mid-gut that functions in protection against mechanical and chemical damage and serves as a barrier to infection by pathogens [46].…”

Role of phenazines and cyclic lipopeptides produced by pseudomonas sp. CMR12a in induced systemic resistance on rice and bean

“…Phenazines and CLPs produced by Pseudomonas sp. CMR12a are not only important in direct antagonism against soilborne pathogens as was shown before (Olorunleke et al ., ), but also play a role in enhancing plant innate immunity. Their action, however, is plant‐pathosystem and concentration dependent.…”

Leuconostoc spp. Associated with Root Rot in Sugar Beet and Their Interaction with Rhizoctonia solani

“…and R. solani. Other investigations studying R. solani on sugar beet and other crops have been focused on investigating bacteria in an effort to develop a biocontrol to limit disease development by the fungus (De Curtis et al 2010;Gkarmiri et al 2015;Heydari and Misaghi 2003;Hua and Höfte 2015;Lovic et al 1993;Mendes et al 2011;Olorunleke et al 2015;Postma and Schilder 2015;Postma et al 2010;Schillinger and Paulitz 2014;Solanki et al 2012;Weller et al 2002;Yin et al 2013;Zachow et al 2011).…”