Interspecific Hybrids between Fusarium oxysporum lycopersici and Fusarium graminearum by Mycelial Anastomoses

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Abstract
Fusarium oxysporum lycopersici (FOL) and F. graminearum (FG) developed mycostatin (M) and cycloheximide (C) resistant mutants (FOL[M] and FG[C]) after treatment with nitrosoguanidine. Four hybrids, obtained from hyphal anastomoses between the mutants, were isolated from medium containing both mycostatin and cycloheximide at concentrations which did not permit growth of the mutants or the original parents. Both the mutants and the interspecies hybrids (ISH) derived from them expressed significant differences in pathogenicity to tomato and wheat from that expressed by the parents FOL and FG. Protein, esterase, pectinase and polyphenoloxidase electrophoretograms displayed unique patterns for the hybrids and the mutant parents. However, these patterns did not correlate with the pathogenicity expressions obtained. The study has demonstrated interspecies hybridizations between FOL(M) and FG(C) by hyphal anastomoses. Both the processes of mutation and hybridization altered the expression of pathogenicity in tomato and wheat The significance of these observations on the origin and development of new pathogenic forms is discussed.