Abstract: Mating type and fertility of rice blast fungus population, which consists of 141 isolates collected from Guangdong (GD) Province, China, were characterized by using A and B sets of standard isolates originated from barley and rice, respectively. As for fertility, the frequencies of fertile isolates were 97.7%, 74.2% and 85.5%, respectively, in North, Middle and South GD regions. As for rice-growing season, the frequencies of fertile isolates were 82.8% and 89.6% in early and late seasons respectively. As for mating type, GD population was predominated of MAT1-2. That is, the proportion of MAT1-2 isolates in the fertile part was 98.3%. As for the sexes of isolates, all the fertile isolates were male isolates. In other words, there is no any female and hermaphroditic isolate in the GD population. In regard to the two sets of standard isolates, the frequencies of mating type identified were 86.5% and 4.3% in the GD population by A and B sets, respectively, suggesting that the differentiating capacities of A and B sets of standard isolates are quite different. This result further suggests the genetic background and/or combining ability of standard isolates are important factors in determining mating types and fertilities of heterothalic isolates.

Key words: Magnaporthe grisea, Mating type, Fertility, Standard isolat, Differentiating capacity