Indian Mustard and Allyl Isothiocyanate Inhibit Sclerotium rolfsii

Abstract

ADDITIONAL INDEX WORDS. Brassica, southern blight, soilborne pathogen, biofumigation ABSTRACT. Allyl isothiocyanate (AITC) is the predominant isothiocyanate produced by damaged tissues of Indian mustard (Brassica juncea (L) Czerniak). This study investigated Indian mustard and AITC mediated suppression of mycelial growth and sclerotial germination of Sclerotium rolfsii Saccardo, a common soilborne pathogen. Indian mustard (IM) treatments of 0, 0.1, 0.2, 0.6, 1.0, 2.0, 4.1, 5.1, 10.2, 20.4, 40.8, 81.6, and 163.3 g·L -1 (weight of reconstituted mustard per liter of air) were evaluated for suppression of mycelial growth. Treatment effect was evaluated by measuring the radial growth of mycelia. Sclerotia were placed in culture tubes containing 18 g autoclaved soil and covered with an additional 5 g soil. AITC at concentrations of 0, 4.0, 16.0, 64.0, 256.0, 1024.0, or 4096.0 µmol·L -1 was injected into the tubes. Treated sclerotia were removed from tubes and plated on potato dextrose agar to determine viability. Mycelial growth was inhibited with IM treatments (P < 0.01). Inhibiting concentrations (IC) of IM for mycelial growth inhibition of 50% and 90% were 0.7 and 1.0 g·L -1 , respectively, with death resulting with >2 g·L -1 . Inhibition attributable to AITC alone was lower than that achieved by IM producing equivalent amounts of AITC. Germination of sclerotia was negatively correlated with AITC concentration (r = 0.96; P < 0.01). The IC 50 and IC 90 of AITC were 249.0 and 528.8 µmol·L -1 , respectively, at 42 hours. The lethal concentration for sclerotia was not reached; only suppression occurred at the highest treatment concentrations. Sclerotium rolfsii mycelia were sensitive to the IM volatiles and were suppressed at low concentrations. Sclerotia were more resistant than the mycelia and required higher concentrations of AITC to suppress germination.

Control, byBrassicaseed pomace combined withPseudomonas boreopolis, of damping-off of watermelon caused byPythiumsp.

“…Pfender & D.J. Hagedorn (Smolinska et al 1997), Sclerotium rolfsii (Harvey et al 2002), and Fusarium sambucinum Fuckel (Mayton et al 1996).…”

Analysis of the isothiocyanates present in cabbage leaves extract and their potential application to control Alternaria rot in bell peppers

“…As an example, AITC is suppressive to many species of fungi (Charron & Sams, 1999;Harvey et al, 2002;Mayton et al, 1996). Benzyl ITC and 3-methylsulWnylpropyl ITC suppressed 100% of A. alternata growth at concentrations of 0.55 and 1.2 mg/ml, respectively (Manici et al, 1997).…”

“…It had been found that isothiocyanates can be toxic to fungi (Charron & Sams, 1999;Harvey, Hannahan, & Sams, 2002;Smolinska, Morra, Knudsen, & James, 2003), bacteria (Delaquis & Mazza, 1995), nematodes and insects (Kermanshai et al, 2001).…”

Biofumigation To Manage Plant-Parasitic Nematodes

“…However, results from a number of studies indicated that the content of glucosinolates in the biofumigant material did not predict the biocidal activity (Angus et al, 1994;Bending & Lincoln, 1999;Charron & Sams, 1999;Harvey, Hannahan, & Sams, 2002;Lazzeri & Manici, 2001;McLeod & Steel, 1999;Morra & Kirkegaard, 2002). One reason for this apparent discrepancy could be that the conversion of glucosinolates into the biocidal ITCs is low.…”