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Physiology and Biochemistry

Acidic and Basic Extracellular Pathogenesis-Related Leaf Proteins from Fifteen Potato Cultivars. Jean- Guy Parent, Département de phytologie, Faculté des sciences de l’agriculture et de l’alimentation, Université Laval, Québec, Canada G1K 7P4, Present address: Service de recherche en phytotechnie de Québec, Ministère de l’Agriculture, des Pêcheries et de l’Alimentation, Complexe scientifique, 2700 rue Einstein, Ste-Foy, Québec, Canada G1P 3W8; Alain Asselin, Département de phytologie, Faculté des sciences de l’agriculture et de l’alimentation, Université Laval, Québec, Canada G1K 7P4. Phytopathology 77:1122-1125. Accepted for publication 31 December 1986. Copyright 1987 The American Phytopathological Society. DOI: 10.1094/Phyto-77-1122.

Fifteen potato cultivars (Avon, Bintje, Cherokee, Green Mountain, Hudson, Jemseg, Kennebec, Nooksack, Norchip, Norland, Sable, Saco, Sebago, Superior, and Yukon Gold) produced necrotic local lesions on leaves inoculated with high concentrations (20 mg/ml) of U₂ tobacco mosaic virus. Proteins in the intercellular fluid extracts from inoculated leaves were characterized by native and denaturing polyacrylamide gel electrophoresis, gel filtration, and chromatofocusing. The presence of glycoproteins was also tested. Nine acidic (apparent isoelectric points [pI] 3.95–5.60), low molecular weight (28,200–40,700) soluble proteins, and six major basic proteins (apparent pI 7.2–9.2, M_r 14,100–33,300) were found in addition to several minor ones. Four acidic proteins with R_f 0.54 (M_r 38,900, apparent pI 3.95), 0.56 (M_r 40,700, apparent pI 4.10), 0.59 (M_r 40,700, apparent pI 4.0), and 0.62 (M_r 40,700, apparent pI 3.95) could be used as genetic markers to identify cultivars. No acidic proteins were observed that were equivalent to the b₁, b₂, and b₃ (pathogenesis-related la, b, c) proteins found in various Nicotiana species. Three acidic peroxidases (glycoproteins) (R_f 0.09, 0.39, and 0.42) were identified.