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Etiology

Induction of Common Scab Symptoms in Aseptically Cultured Potato Tubers by the Vivotoxin, Thaxtomin. C. H. Lawrence, Research Station, Agriculture Canada, Fredericton, New Brunswick, Canada E3B 4Z7; M. C. Clark(2), and R. R. King(3). (2)Tweedale Centre, University of New Brunswick, Fredericton, New Brunswick, Canada E3B 6H6; (3)Research Station, Agriculture Canada, Fredericton, New Brunswick, Canada E3B 4Z7. Phytopathology 80:606-608. Accepted for publication 5 January 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-606.

Inoculation of aseptically cultured minitubers with cell-free extracts from scab lesions of field-grown and cultured tubers infected with Streptomyces scabies reproduced symptoms typical of the common scab disease. Isolation and fractionation of the active components in tissue extracts by a combination of normal and reversed phase thin-layer chromatography yielded two active compounds. These have been designated thaxtomin A and thaxtomin B and characterized as unique 4-nitroindol-3-yl containing 2,5-dioxopiperazines. These phytotoxic principles satisfy all of the basic criteria of vivotoxins.