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Physiology and Biochemistry

Multiple Forms of Endo-Pectate Lyase Formed in Culture and in Infected Squash Hypocotyls by Hypomyces solani f. sp. cucurbitae. J. G. Hancock, Associate Professor, Department of Plant Pathology, University of California, Berkeley 94720; Phytopathology 66:40-45. Accepted for publication 10 July 1975. DOI: 10.1094/Phyto-66-40.

Differences in several physical properties were found between endo-pectate lyase produced by Hypomyces solani f. sp. cucurbitae in culture and that produced in Hypomyces-infected squash (Cucurbita maxima). Endo-pectate lyase from culture and infected tissue possessed isoelectric points of 10.2-10.3 and 10.5-10.6, respectively, and the heat stability of purified endo-pectate lyase from culture was much greater than that of similar preparations from infected tissue. These differences, together with disparities in catalytic properties, indicate that enzymic activities of endo-pectate lyase from culture and infected tissue represent multiple molecular forms. Dichotomy in forms of endo-pectate lyase produced by H. solani f. sp. cucurbitae in culture and during pathogenesis may reflect either fungal adaptation to different environments or postsynthetic modification of the enzyme.