Oxidative burst elicited by Bacillus mycoides isolate Bac J, a biological control agent, occurs independently of hypersensitive cell death in sugar beet

• Published in: Molecular plant-microbe interactions Vol. 16; no. 12; pp. 1145 - 1153
• Main Authors: Bargabus, R.L, Zidack, N.K, Sherwood, J.E, Jacobsen, B.J
• Format: Journal Article
• Language: English
• Published: St Paul, MN APS Press 01-12-2003; American Phytopathological Society; The American Phytopathological Society
• Subjects: Bacillus - physiology; Bacillus mycoides; Beta vulgaris; Beta vulgaris - cytology; Beta vulgaris - microbiology; Beta vulgaris - physiology; Biological and medical sciences; biological control; biological control agents; Cell Death - physiology; Cercospora beticola; chitinase; defense mechanisms; disease resistance; enzyme activity; Erwinia carotovora; Fundamental and applied biological sciences. Psychology; fungal antagonists; Hydrogen Peroxide - metabolism; oxidative burst; Pectobacterium carotovorum - pathogenicity; Pectobacterium carotovorum subsp. betavasculorum; Pest Control, Biological; Phytopathology. Animal pests. Plant and forest protection; plant pathogenic bacteria; plant pathogenic fungi; Respiratory Burst; sugar beet; systemic acquired resistance; Virulence; Microbiology; Bacillus mycoides; Biological control; Bacillaceae; Beta vulgaris var. saccharata; Chenopodiaceae; Bacillales; Cell death; Dicotyledones; Angiospermae; Bacteria; Isolate; Spermatophyta
• ISSN: 0894-0282; 1943-7706
• DOI: 10.1094/MPMI.2003.16.12.1145

Response of sugar beet cultivars C40 and USH11 to syringe infiltration of live and dead Bacillus mycoides isolate Bac J, a biological control agent, and virulent and avirulent isolates of Erwinia carotovora pv. betavasculorum was measured by monitoring systemic acquired resistance control of Cercospora beticola, specific activity of chitinase and beta-glucanase, the oxidative burst, and hypersensitive cell death at the infiltration site. Priming sugar beet with B. mycoides Bac J (1 x 10(8) cells/ml) and avirulent isolates of E. carotovora pv. betavasculorum (1 x 10(6) cells/ml) reduced C. beticola symptoms by nearly 70% on distal, untreated leaves. Systemic resistance responses elicited by live B. mycoides Bac J and avirulent E. carotovora pv. betavasculorum isolates, measured by assays for chitinase and beta-glucanase, were statistically equivalent, and biphasic hydrogen peroxide production was observed. Although similar in timing, the second hydrogen peroxide burst was twofold lower for B. mycoides Bac J than for avirulent E. carotovora pv. betavasculorum. Hypersensitive cell death was elicited by avirulent E. carotovora pv. betavasculorum but not B. mycoides Bac J. An oxidative burst was elicited by spray-applied B. mycoides Bac J under both light and green light conditions, indicating that the signal produced by B. mycoides Bac J was not reliant on the stomata for entry into sugar beet. A working model for signal delivery and systemic resistance induction by B. mycoides Bac J in sugar beet is proposed.