Abstract: PWL gene family belongs to the host\|specific resistance avirulence gene， which is an important avirulence gene in Magnaporthe grisea. To understand distribution and variability of PWL family in rice blast fungus was useful for the genetic diversity research of Magnaporthe grisea， however， there was few studies on the distribution and variability of host-specific avirulence PWL family genes in rice blast fungus Magnaporthe grisea. We designed 23 pairs of primers to character the distribution and variability of PWL gene and screened 12 pairs of specific primers of PWL family genes which have specific amplifications. Our results showed that the main mutation mechanism of PWL family genes was deletion. The PWL1 gene existed only in the strains isolated form Eleusine， while the corresponding locus of strains isolated from rice was completely missing; in contrast， PWL2 gene was only in the strain isolated from rice. Insertion mutation existed only in the upstream region of PWL4 gene. Our results suggest that PWL family genes has a rich amplified polymorphic and has a good basis for population genetic diversity analyses.

Key words: Magnaporthe grisea, PWL gene family, mutation