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Genetics of Certain Morphological Characteristics in Gibberella baccata. E. B. Lawrence, Former graduate research assistant, Fusarium Research Center, The Pennsylvania State University, University Park 16802, Present address: Monsanto Agricultural Products Co., 800 N. Lindbergh, St. Louis, MO 63166; Paul E. Nelson(2), and T. A. Toussoun(3). (2)(3)Professors of plant pathology, Fusarium Research Center, The Pennsylvania State University, University Park 16802. Phytopathology 75:741-747. Accepted for publication 11 February 1985. Copyright 1985 The American Phytopathological Society. DOI: 10.1094/Phyto-75-741.

Variation in colony morphology is common in the genus Fusarium. The most commonly encountered cultural mutants in Gibberella baccata (Fusarium lateritium) are pionnotal; they produce conidia in pionnotes rather than in sporodochia. Sporodochial and pionnotal isolates of F. lateritium were crossed in all possible combinations and the progeny were rated for colony morphology. Both random ascospores and unordered tetrads were studied. Production of pionnotes versus sporodochia was controlled by two linked genes. Only one arrangement of alleles resulted in sporodochial formation. Genes controlling growth rate, color, and degree of aerial mycelium development were on the same linkage group as those controlling pionnote formation. Epistasis was evident between genes controlling pionnote formation and aerial mycelium production; pionnotal isolates had reduced amounts of aerial mycelium. The unlinked genes for mating type and sexual expression were inherited independently from the genes controlling pionnote versus sporodochial production. Production of mycelial mutants was controlled by one gene.