Amino acid induction of conidiation and morphological alterations in wild type and morphological mutants of Neurospora crassa.

Abstract

Casamino acids, utilized in a growth medium as sole source of both carbon and nitrogen strikingly changed the morphology of wild type and several morphological mutants of Neurospora. Some of the changes that were seen include: (1) loss of colonial characteristic; (2) stimulation of conidiation (even in a strain previously thought aconidial); (3) modification of mycelial branching; (4) pigment changes. Certain other morphological mutants responded weakly or not at all to the casamino acids media. Of the group which did respond however, addition of certain sugars negated partially or completely the effect of the casamino acids while other carbon sources such as pyruvate, acetate, and Krebs cycle intermediates had no effect. Electron micrographs of the morphological mutant “amycelial” revealed important modifications of the cell wall and endoplasmic reticulum accompanying an induction of conidiation using the casamino acids system or the acetate+succinate combination.