Ophiostoma multiannulatum

The mutagenic effect of caffeine was detected in 1948 independently by Fries and Kihlman (1948) and by Witkin (quoted by Demerec, 1949), using as experimental materials the fungus Ophiostoma multiannulatum and the bacterium Escherichia coli respectively. The chromosome-breaking effect of caffeine was demonstrated in plants by Kihlman and Levan (1949) and in mammalian cells by Ostertag et aL (1965). 

In 1948, Fries and Kihlman in Sweden reported the production of auxotrophic mutations in the ascomycete Ophiostoma multiannulatum by prolonged immersion of the conidia in solutions of caffeine (0.2%) or theophylline (0.6%). Either treatment yielded about 1% auxotrophs at survival levels of about 0.2% control mutation frequencies were very low. Qualitatively, the results were especially interesting because they showed a difference between the mutational spectra induced by these two purines on the one hand and X-irradiation on the other. This was most striking for inositol requirers, which formed less than 5% of radiation-induced auxotrophs but more than 40% of purine-induced ones. This is one of the rare cases of mutagen specificity for a whole locus or biochemical pathway. Like similar cases that were subsequently reported from the same laboratory, it may rest on selective effects of the plating medium, amplified by the previous treatment of the plated conidia. 

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