Induction of systemic disease resistance and pathogen defence responses in Asparagus officinalis inoculated with nonpathogenic strains of Fusarium oxysporum |
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Authors: | C Y He T Hsiang D J Wolyn † |
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Institution: | ;Department of Plant Agriculture and ;Department of Environmental Biology, University of Guelph, Guelph, ON N1G 2W1, Canada |
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Abstract: | The ability of nonpathogenic isolates of Fusarium oxysporum (np Fo ) to induce systemic resistance and defence responses against subsequent challenge with a pathogenic strain of F. oxysporum f. sp. asparagi ( Foa ) was examined in Asparagus officinalis . In a split-root experiment, roots inoculated with np Fo exhibited a hypersensitive response and those subsequently inoculated with Foa displayed resistance. Induction of systemic resistance in np Fo -treated plants led to significantly fewer necrotic lesions ( P = 0·05) and reduced Foa disease severity compared with plants not treated with np Fo . In hyphal-sandwich root inoculation experiments, activities of peroxidase and phenylalanine ammonia-lyase and lignin content were higher in np Fo -treated plants and increased more rapidly than in np Fo -untreated plants after Foa inoculation. Antifungal activity (inhibition of fungal spore germination and germ-tube growth) from exudates of roots inoculated with Foa were observed for np Fo -treated plants but not for np Fo -untreated plants. Thus, isolates of np Fo may function as inducers of systemic acquired resistance (SAR) and defence responses against Foa invasion in A. officinalis . |
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Keywords: | asparagus defence responses Fusarium crown and root rot Fusarium oxysporum f sp asparagi systemic acquired resistance |
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