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Study of the Role of Antimicrobial Glucosinolate-Derived Isothiocyanates in Resistance of Arabidopsis to Microbial Pathogens
Auteur(s)
Tierens, Koenraad F.M.-J.
Thomma, Bart P.H.J.
Brouwer, Margreet
Schmidt, Jürgen
Kistner, Katherine
Porzel, Andrea
Cammue, Bruno P.A.
Broekaert, Willem F.
Date de parution
2001
In
Plant Physiology, American Society of Plant Biologists, 2001/125/4/1688-1699
Résumé
Crude aqueous extracts from Arabidopsis leaves were subjected to chromatographic separations, after which the different fractions were monitored for antimicrobial activity using the fungus <i>Neurospora crassa</i> as a test organism. Two major fractions were obtained that appeared to have the same abundance in leaves from untreated plants versus leaves from plants challenge inoculated with the fungus <i>Alternaria brassicicola</i>. One of both major antimicrobial fractions was purified to homogeneity and identified by 1H nuclear magnetic resonance, gas chromatography/electron impact mass spectrometry, and gas chromatography/chemical ionization mass spectrometry as 4-methylsulphinylbutyl isothiocyanate (ITC). This compound has previously been described as a product of myrosinase-mediated breakdown of glucoraphanin, the predominant glucosinolate in Arabidopsis leaves. 4-Methylsulphinylbutyl ITC was found to be inhibitory to a wide range of fungi and bacteria, producing 50% growth inhibition in vitro at concentrations of 28 μm for the most sensitive organism tested (<i>Pseudomonas syringae</i>). A previously identified glucosinolate biosynthesis mutant, <i>gsm1-1</i>, was found to be largely deficient in either of the two major antimicrobial compounds, including 4-methylsulphinylbutyl ITC. The resistance of <i>gsm1-1</i> was compared with that of wild-type plants after challenge with the fungi <i>A. brassicicola</i>, <i>Plectosphaerella cucumerina</i>, <i>Botrytis cinerea</i>, <i>Fusarium oxysporum</i>, or <i>Peronospora parasitica</i>, or the bacteria <i>Erwinia carotovora</i> or <i>P. syringae</i>. Of the tested pathogens, only <i>F. oxysporum</i> was found to be significantly more aggressive on <i>gsm1-1</i> than on wild-type plants. Taken together, our data suggest that glucosinolate-derived antimicrobial ITCs can play a role in the protection of Arabidopsis against particular pathogens.
Identifiants
Type de publication
journal article
