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Physiology and Biochemistry

Phytotoxin(s) Produced in Culture by the Pierce’s Disease Bacterium. R. F. Lee, University of Florida, Institute of Food and Agricultural Sciences, Agricultural Research and Education Center, Lake Alfred 33850; B. C. Raju(2), G. Nyland(3), and A. C. Goheen(4). (2)(3)Department of Plant Pathology, University of California, Davis 95616; (4)Agricultural Research Service, U.S. Department of Agriculture, University of California, Davis 95616. Phytopathology 72:886-888. Accepted for publication 14 December 1981. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-886.

A phytotoxin that caused burning and scorching of leaves of grape, almond, and plum was obtained by washing cell cultures of rickettsialike bacteria that had been isolated from grapevines affected with Pierce’s disease (PD), almond affected with almond leaf scorch, and alfalfa affected with alfalfa dwarf. Detached leaves and leaves on dormant and rooted grape cuttings treated with a bacteria-free solution of toxin developed scalding and necrosis on the leaf margins, symptoms that are characteristic of PD. Although no bacteria were present in the solution containing the toxin, they were easily isolated from rooted and nonrooted leafy cuttings similarly treated with cell suspensions of the bacteria. Leaves and shoots of other woody and herbaceous plants bioassayed with the toxin were not visibly affected, except for periwinkle and Eureka lemons, which showed general wilting.