The General Secretory Pathway of Burkholderia gladioli pv. agaricicola BG164R Is Necessary for Cavity Disease in White Button Mushrooms

Abstract

Cavity disease in white button mushrooms is caused by Burkholderia gladioli pv. agaricicola. We describe the isolation and characterization of six mutants of the strain BG164R that no longer cause this disease on mushrooms. The mutations were mapped to genes of the general secretory pathway (GSP). This is the first report of the association of the type II secretion pathway with a disease in mushrooms. Phenotypes of the six avirulent mutants were the following: an inability to degrade mushroom tissue, a highly reduced capacity to secrete chitinase and protease, and a reduced number of flagella. Using these mutants, we also made the novel observation that the factors causing mushroom tissue degradation, thereby leading to the expression of cavity disease, can be separated from mycelium inhibition because avirulent mutants continued to inhibit the growth of actively growing mushroom mycelia. The GSP locus of B. gladioli was subsequently cloned and mapped and compared to the same locus in closely related species, establishing that the genetic organization of the gsp operon of B. gladioli pv. agaricicola is consistent with that of other species of the genus. We also identify the most common indigenous bacterial population present in the mushroom fruit bodies from a New Zealand farm, one of which, Ewingella americana, was found to be an apparent antagonist of B. gladioli pv. agaricicola. While other investigators have reported enhanced disease symptoms due to interactions between endogenous and disease-causing bacteria in other mushroom diseases, to the best of our knowledge this is the first report of an antagonistic effect.

Infection Prevention and Control Guideline for Cystic Fibrosis: 2013 Update

“…Other species, particularly Burkholderia ambifaria, exist within the rhizospheres of certain plants, while B. multivorans is infrequently recovered from the environment. [292][293][294][295][296] Several investigations since the publication of the 2003 Infection Control Guideline for CF have enhanced our understanding of the potential role played by the natural environment in the acquisition of CF pathogens and possible strain-specific reservoirs.…”

The Type 2 Secretion Pseudopilin, gspJ , Is Required for Multihost Pathogenicity of Burkholderia cenocepacia AU1054

“…T2SS was found to be required for B. gladioli pathogenicity to mushrooms (14). In addition, the genome sequence of the ET12 epidemic clone strain, J2315, revealed a 110-bp insertion in gspL required for T2SS function (34).…”

“…Type 2 secretion systems (T2SSs) are required for the secretion of many toxins and enzymes that contribute to virulence, notably exotoxin A and cholera toxin produced by P. aeruginosa and Vibrio cholerae, respectively (23,62). Previous studies did not detect a significant defect in virulence of B. pseudomallei, B. cenocepacia, and B. vietnamiensis strains mutant in T2SS, although the T2SS is required for B. gladioli pathogenicity to mushrooms (14,21,24,41). However, expression of the T2SS genes was found to be induced in synthetic CF sputum medium relative to soil extract by strains AU1054 and J2315; although the latter was unexpectedly found to have a 110-bp deletion in gspL, known to be required for T2SS function (34,73,74).…”

Avaliação de bactérias endofíticas para o controle biológico da mancha foliar de Exserohilum turcicum em milho

“…Embora não se tenha observado a ocorrência de Ewingella americana como agente de biocontrole de fitopatógenos, há relatos da sua aparente ação micopatogênica e quitinolítica a Burkholderia gladioli pv. agaricicola e a Agaricus bisporus, Lentinula edodes e Pleurotus ostreatus (Chowdhury;Heinemann, 2006;Reyes et al, 2004). Não foram encontrados relatos da ação de X. axonopodis no controle de fitopatógenos.…”