VIEW ARTICLE

Ecology and Epidemiology

Distribution of the Mating Type Alleles in Magnaporthe grisea Populations Pathogenic on Rice. J. L. Notteghem, Institut de Recherches en Agronomie Tropicale, Avenue du Val de Montferrand, Laboratoire de Phytopathologie, 34032 Montpellier CEDEX, France; D. Silué, Institut de Recherches en Agronomie Tropicale, Avenue du Val de Montferrand, Laboratoire de Phytopathologie, 34032 Montpellier CEDEX, France. Phytopathology 82:421-424. Accepted for publication 17 September 1991. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/Phyto-82-421.

Four hundred sixty-seven Magnaporthe grisea isolates were collected from rice in 34 countries. Each isolate was tested for mating type with two MAT1-1 and two MAT1-2 fertile (hermaphroditic) standard isolates. Thirty-two percent of these isolates are MAT1-1, and 20% are MAT1-2. The remaining 48% do not produce perithecia with any of the four fertile testers. In most locations, only one mating type was present. In two locations (one in Ivory Coast and one in Cameroon), isolates of both mating types were found, but they were intersterile. Almost all the isolates had very low fertility, because they were, in general, female sterile and sometimes also male sterile. Few crosses were fertile enough to permit the isolation of germinating ascospores. Crosses between the hermaphroditic isolate GUY11 and three other male isolates gave ascospore progeny with mating type that segregated 1:1 among the progeny. This suggests that these isolates could be used for the genetic analysis of pathogenicity.