Isothiocyanates Produced by Brassicaceae Species as Inhibitors of Fusarium oxysporum

Abstract

Glucosinolates contained in members of the Brassicaceae release isothiocyanates potentially useful in controlling Fusarium oxysporum pathogens in conifer seedling nursery soils. Our objective was to determine the toxicity of individual isothiocyanates to different growth stages of the fungus. Bioassays with four F. oxysporum isolates were conducted using sealed containers in which 0.3 μl of 2-propenyl, ethyl, buty, phenylethyl, benzyl, or phenyl isothiocyanate was allowed to volatilize. Propenyl and ethyl isothiocyanates were the most fungistatic of those compounds tested. The same concentrations of propenyl and ethyl isothiocyanates that inhibited mycelial growth completely suppressed conidial and chlamydospore germination of all isolates. Other isothiocyanates including ethyl, benzyl, and phenethyl were also fungitoxic to F. oxysporum conidia and chlamydospores. Reduction in pathogen populations resulting from a green-manure crop are likely achievable since chlamydospores are sensitive to isothiocyanate. Pathogenic F. oxysporum isolates infesting nursery soils would likely be most suppressed by species of plants such as Brassica carinata, B. nigra, and B. juncea, which contain glucosi-nolates that release high concentrations of propenyl isothiocyanate.

In vitro antifungal activity of brassinin, camalexin and two isothiocyanates against the crucifer pathogens Alternaria brassicicola and Alternaria brassicae

“…Comparable results were reported by Smolinska et al (2003) who showed that five different ITCs, including AlITC, had no significant effect on formation of conidia of Fusarium oxysporum.…”

Brassicaceae cover crops reduce Aphanomyces pea root rot without suppressing genetic potential of microbial nitrogen cycling

“…Our results suggest that only the type and amount of ITCs originating from S. alba intact roots were important for reducing the development of pea root rot by suppressing A. euteiches. Several studies have shown that aliphatic ITCs exhibit a stronger toxic effect than the aromatic ITCs (Sarwar et al 1998;Smolinska et al 2003;Matthiessen and Shackleton 2005;Hossain et al 2014). Nevertheless, the aromatic 2-phenylethyl ITC detected in the B. juncea treatment is known to have toxic effects on several organisms, including mycelium growth of A. euteiches as shown by in-vitro tests using synthetic 2 phenylethyl dissolved in a fungal growth medium (Smith and Kirkegaard 2002).…”

“…When the GSLs are hydrolysed by the endogenous enzyme myrosinase, volatile isothiocyanates (ITCs), thiocyanates and water-soluble nitriles and epithionitriles are formed (Brown and Morra 1997;Kiddle et al 2001). These products are toxic to soilborne pathogens (Kirkegaard et al 2000;Potter et al 2000;van Dam et al 2009), but the suppressive effect depends on their chemical composition (Smolinska et al 2003;Matthiessen and Shackleton 2005) and concentration (Angus et al 1994;Sarwar et al 1998;Hossain et al 2014). For the pea root rot pathogen A. euteiches, in-vitro experiments have demonstrated reduced hyphal growth caused by volatiles from Brassica napus rapeseed meal (cv.…”

Efecto del jugo de brócoli y cambios químicos en la inhibición de Alternaria en arúgula mínimamente procesada

“…El brócoli es la principal fuente natural del isotiocianato sulforafano (1-isotiocianato-4-(metilsulfinil)-butano), su precursor glucorafanina constituye más de 80% de los glucosinolatos totales presentes en este vegetal (Campas-Baypoli et al, 2009). Se ha comprobado que los isotiocianatos tienen la propiedad de controlar el crecimiento de microorganismos patógenos tales como Fusarium oxysporum, (Smolinska et al, 2003), Alternaria rot , Rhizopus nigricans (Mucete et al, 2006) Penicillium expansum …”