The Control of Conidial Differentiation in Neurospora crassa

Abstract

SUMMARY: The ability of a culture of Neurospora crassa to produce a macroconidium or a microconidium is determined (irreversibly) at a particular period during development. The determinative periods for macroconidiation and microconidiation are not always coincident. In some strains, prevention of conidial formation for a period encompassing the earlier of the two determinative periods, followed by a removal of the restriction allowing conidiation to proceed, causes a complete switch in the conidial character, so that strains which are normally macroconidiate may be induced to produce only microconidia. The phenotypic changes are not due to permanent genetic changes in the cultures. This phenomenon was observed only when normal growth proceeded during the time when conidial differentiation was prevented.