A survey of new morphological mutants in Neurospora crassa.

HIS investigation of morphological mutants in Neurospora crassa was underTtaken to examine a wide spectrum of such strains and to obtain information regarding their number and distribution in each of the seven linkage groups. This information, as well as a comparative study of their morphological characteristics, is important both theoretically and practically in facilitating further investigations of the biochemical defects involved. The present report describes the linkage to known markers of 90 morphological strains of independent origin. Of these, 58 have designated as new loci; the remainder appear to represent alleles either of the new or previously described loci. The order of the genes has been determined only in group V (MORGAN, GARNJOBST and TATUM 1967). The differences between strains in type of mycelial growth, both from the ascospore and upon transfer, and the distinct differences between some strains in hyphal morphology have suggested a new and practical classification of the morphological mutants. Six classes are defined, illustrated, and discussed.