VIEW ARTICLE

Physiology of Sexual Reproduction in Hypomyces solani f. sp. cucurbitae VI. The Effects of Tyrosinase and Cold Treatment on Cellular Permeability. David M. Wilson, Department of Botany and Plant Pathology, Colorado State University, Fort Collins 80521, Present address: Department of Botany, University of Vermont, Burlington 05401. Phytopathology 60:129-131. Accepted for publication 25 August 1969. DOI: 10.1094/Phyto-60-129.

Cultures of Hypomyces solani f. sp. cucurbitae, race 1, were exposed to 4ºC or were treated with tyrosinase at 10 days to study the effects of these treatments on cellular permeability and cellular tyrosine. Leakage values from cultures growing in potato-dextrose broth were similar after the cold treatment or enzyme treatment. There was less K+ leakage, more Mg++ leakage, and more amino acid leakage from the treated cultures than from the control cultures. No differences were observed in the Na+ and Ca++ leakages. There was a decrease in the free tyrosine 1 day after either treatment, but 5 days after either treatment, control and treated cultures were similar. Less tyrosine was found in protein hydrolysates from treated cultures than from nontreated cultures, but recovery was complete within 10 days after treatment. These results support the hypothesis that extracellular tyrosinase alters membrane permeability. This permeability change may be the initial factor in the differentiation processes involved in the stimulation of the production of perithecial primordia, with melanin production being of secondary importance. There is no evidence than this mechanism is responsible for maintaining the permeability differences observed.