Isolation of Mutants Resistant to some Chemicals from Sunlight –Exposed and Unexposed Samples of the Fungus Alternaria alternata

Abstract

A total of 272 mutants (161 from sunlight exposed and 111 from unexposed conidia) resistant to the chemicals Topas, 8-azaguanine or Chloral hydrate were Isolated in the fungus Alternaria alternata. Initially, the exposure periods to sunlight and the minimal inhibitory concentrations for the chemicals were determined. The exposure periods were 20, 40, 60 and 90 minutes and the minimal inhibitory concentrations were 150 µg/ml for Topas, 3.5 µg/ml for 8-azaguanine and 4.5 mM for Chloral hydrate. The frequency of mutants resistant to each chemical was calculated and although the frequencies from the exposed samples were greater than those from unexposed one, the differences, however, were