VIEW ARTICLE

Physiology and Biochemistry

Effect of Tricyclazole on Appressorial Pigmentation and Penetration from Appressoria of Colletotrichum lagenarium. Y. Kubo, Laboratory of Plant Pathology, Faculty of Agriculture, Kyoto University, Kyoto 606, Japan; K. Suzuki(2), I. Furusawa(3), and M. Yamamoto(4). (2)(3)(4) Laboratory of Plant Pathology, Faculty of Agriculture, Kyoto University, Kyoto 606, Japan. Phytopathology 72:1198-1200. Accepted for publication 19 February 1982. Copyright 1982 The American Phytopathological Society. DOI: 10.1094/Phyto-72-1198.

Tricyclazole (5-methyl-1,2,4-triazole (3,4-b) benzothiazole) inhibited pigmentation of appressoria at concentrations higher than 1 μM in Colletotrichum lagenarium, and the color of appressoria varied from dark brown to light brown depending on tricyclazole concentrations. In the presence of 100μM tricyclazole, appressorial pigmentation was completely inhibited. The colorless appressoria germinated laterally and consequently could not penetrate nitrocellulose membranes. Furthermore, tricyclazole treatment after appressorial pigmentation did not affect penetration into the membranes. These characteristics of appressoria formed in the presence of tricyclazole were the same as those of an albino mutant. On host leaves, colorless appressoria formed in the presence of tricyclazole and those of the albino mutant did not penetrate the host plant cell wall. From these findings, it is concluded that pigmentation of appressoria is essential for host penetration by C. lagenarium.