Effects of Temperature on Reversion Rate of Ustilago maydis

Abstract

The reversion rates per unit time of homocysteineless strains of Ustilago maydis were determined at seven or eight temperatures. The temperature coefficients were 3.9, 2.2 and 1.8 and activation energies, 0.92, 0.65, and 0.42ev respectively.
The relationships between reversion rate and activation energy, and between frequency factor and activation energy were analyzed. It was suggested that the various mutants have a pseudoallelic nature.
The authors wish to express their thanks to Dr. F. J. Ryan for his helpful advice and suggestions given in this work and thanks are also due to Dr. D. D. Perkins who has kindly supplied the original strains of Ustilago maydis.