The blast disease caused by Pyricularia grisea (teleomorph Magnaporthe grisea) has a wide host range. In Brazil, significant yield loss has been reported in rice, wheat, triticale and barley crops. Besides those cereals, several other gramineous plants have been shown to develop symptoms of this disease. The objectives of this research were: a) sexually characterize isolates of P. grisea from these hosts based on the mating type, fertility, sexuality, sexual compatibility, b) to analyze the degree of sexual compatibility among isolates from wheat and other grasses, c) to verify the occurrence of sexual reproduction in isolates from wheat. Results of "in vitro" assay showed: 1) sexual compatibility of P. grisea of wheat with isolates of the fungus obtained from Bromus catharticus, Phalaris canariensis e X. triticosecale, 2) a skewed distribution of mating type, with predominance of MAT1-1,0020in blast population from wheat, 3) the existence of isolates of low crossing ability in a wheat field, 4) a low possibility of sexual recombination in wheat isolates despite the existence of both mating type in the same field.
blast; hosts; recombination; Magnaporthe grisea
