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Genetics

Identification of Magnaporthe grisea Avirulence Genes to Seven Rice Cultivars. D. Silué, Laboratoire de phytopathologie CIRAD/CA, BP 5035, 34032 Montpellier Cedex, France; D. Tharreau, and J. L. Notteghem. Laboratoire de phytopathologie CIRAD/CA, BP 5035, 34032 Montpellier Cedex, France. Phytopathology 82:1462-1467. Accepted for publication 30 June 1992. Copyright 1992 The American Phytopathological Society. DOI: 10.1094/Phyto-82-1462.

To characterize the inheritance of avirulence in Magnaporthe grisea to specific rice cultivars, we performed a cross between two field isolates pathogenic to rice. Full-sib crosses followed by backcrosses enhanced the fertility of some matings so that tetrads could be isolated. Genetic analysis of avirulence to the rice cultivars Cica 6, Cica 8, DJ 8-341, IRAT 7, Ku 86, Med Noï, and Tetep was performed with these crosses. Avirulence to rice cultivars DJ 8-341, IRAT 7, Ku 86, and Tetep is controlled by one gene. Two genes are involved in avirulence to rice cultivars Cica 6, Cica 8, and Med Noï. Each of the two segregating genes acts independently and is sufficient to confer avirulence. This is the first report of such a control of avirulence in M. grisea. Linkages between avirulence genes and MAT1 and between avirulence genes are suspected. At least six avirulence genes are described.