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Genetics

Interspecific Crosses Between Closely Related Heterothallic Phytophthora Species. B. R. Boccas, Plant pathologist, Office de la Recherche Scientifique et Technique Outre-Mer, B.P. A 5 Nouméa, New Caledonia.; Phytopathology 71:60-65. Accepted for publication 14 May 1980. Copyright 1981 The American Phytopathological Society. DOI: 10.1094/Phyto-71-60.

Five crosses between closely related heterothallic Phytophthora species produced oospores, a low percentage (1–5%) of which germinated. Colony morphology, optimum and maximum growth temperatures, growth rate, pathogenicity, and composition in soluble porteins among the progeny were studied. Among these single oospore isolates, only one, from a cross between P. capsici and P. palmivora appeared to be a product of interspecific hybridization. All other crosses resulted in phenotypically heterogeneous progeny that exhibited recombination for some morphological, physiological and pathogenic characters; their protein patterns, however, were of a single parental type. These results suggest that the progeny resulted from the self-fertilization of diploid heterozygous parental strains rather than from hybridization.