Abstract
Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) pattern of heat-shock protein 70A gene (hsp70A) was examined for 29 isolates of the pinewood nematode. Among them, two known avirulent and five virulent isolates generated banding patterns identical within each of the two isolate groups but distinctive between the two. On the other hand, field populations were collected in two geographical areas, around Kasama City, Ibaraki Prefecture and the southern part of Kujukurihama coast, Chiba Prefecture, Japan. PCR-RFLP image analysis revealed that some of the populations possessed both of the two alleles. The geographical distribution of the alleles was random in the two sampling areas. On the basis of the results, we hypothesize that the avirulent strain might have a certain contribution to the gene pool of the pinewood nematode, although there has been no report on the collection of an avirulent population from Japan recently.
