Several “pathogenesis-related” proteins in potato are 1,3-β-glucanases and chitinases

Chitinase {poly[1,4-(N-acetyl-β-D-glucosaminide)]glycanohydrolase, EC 3.2.1.14} and 1,3-β-glucanase (1,3-β-D-glucan 3-glucanohydrolase, EC 3.2.1.6) activities increased rapidly in potato (Solanum tuberosum) leaves inoculated with the pathogenic fungus Phytophthora infestansor treated with fungal elicitor. The enzyme activities were resolved into a total of two distinct 1,3-β-glucanases and six proteins with chitinase activity. By several criteria, all of these proteins are classified as “pathogenesis-related” proteins whose biochemical functions have so far been unknown. Some of them constitute a major portion of the proteins accumulating in the intercellular space of infected potato leaves and are assumed to play an important role in pathogen defense.