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Physiology and Biochemistry

Relation of Appressorium Pigmentation and Penetration of Nitrocellulose Membranes by Colletotrichum lagenarium. Y. Kubo, Laboratory of Plant Pathology, Faculty of Agriculture, Kyoto University, Kyoto 606, Japan; K. Suzuki(2), I. Furusawa(3), N. Ishida(4), and M. Yamamoto(5). (2)(3)(4)(5)Laboratory of Plant Pathology, Faculty of Agriculture, Kyoto University, Kyoto 606, Japan. Phytopathology 72:498-501. Accepted for publication 20 July 1981. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 1981.. DOI: 10.1094/Phyto-72-498.

Seventeen albino mutants of Colletotrichum lagenarium were obtained by ultraviolet irradiation or treatment with N-methyl--nitro-N-nitrosoguanidine. These mutants formed orange colonies and colorless appressoria, whereas the parent strain formed dark-brown colonies and pigmented appressoria. More than 90% of the mutant appressoria germinated laterally and formed secondary appressoria within 48 hr, and consequently <10% penetrated nitrocellulose membranes within 72 hr. In contrast, appressoria of the parent strain rarely germinated laterally and >70% penetrated the membranes. When conidia of the mutants were incubated in the presence of 3,4-dihydroxyphenylalanine, they behaved like the parent strain, the appressoria became pigmented, lateral germination decreased to 20%, and penetration of membranes increased to 60%. From these results, we conclude that melanin pigments in the appressorial walls are necessary for normal penetration of the host.

Additional keywords: anthracnose, fungal melanin.