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Chlorosis of Tobacco Induced by Alternariol Monomethyl Ether Produced by Alternaria tenuis. R. W. Pero, Research Associate, Department of Plant Pathology, North Carolina State University, Raleigh 27607, Present address of senior author: National Institute of Environmental Health Sciences, Cell Biology Section, Research Triangle Park, North Carolina 27709; C. E. Main, Assistant Professor, Department of Plant Pathology, North Carolina State University, Raleigh 27607. Phytopathology 60:1570-1573. Accepted for publication 1 June 1970. DOI: 10.1094/Phyto-60-1570.

Alternariol monomethyl ether (AME) was isolated from cultures of Alternaria tenuis grown on autoclaved rice grains supplemented with yeast extract and Czapek’s broth. A simplified method for extraction and isolation of AME was developed. AME was also isolated from flue-cured tobacco cultures inoculated with A. tenuis, but was not detected in naturally infected tobacco leaves. AME induced a chlorosis when injected into the leaves of intact tobacco plants. The chlorosis was similar to the characteristic chlorotic halo surrounding natural brown spot lesions. Evidence presented suggests that AME was metabolized by live tobacco leaves. Alternariol monomethyl ether was identified by comparison with authentic AME as to melting point, IR spectral absorption, and chromatographic behavior in four solvent systems. Mass spectrum analysis of isolated AME conformed to the molecular wt and structure reported in the literature. The possible significance of AME in pathogenesis and its relation to tolerance in the brownspot disease of tobacco is discussed.