Genetic diversity of Ganoderma in oil palm plantings

Isolates of Ganoderma spp. associated with basal stem rot of oil palm were obtained by sampling from two palm plantings in Malaysia. Members of a subs et of these were compared using a combination of somatic incompatibility an d molecular genetic analyses. Incompatibility interactions between heteroka ryons in culture indicated that Ganoderma generally occurred as numerous di stinct strains, with compatible strains usually confined to individual palm s. Analysis of restriction fragment length polymorphisms (RFLPs) in presump tive mitochondrial DNA (mtDNA) revealed heterogeneity among isolates from n eighbouring palms, and from within individual palms. The combination of mtD NA variability and somatic incompatibility suggests that Ganoderma BSR does not spread by direct root-to-root contact between palms. The results may i ndicate infection spread through basidiospore dispersal or through contact with a heterogeneous long-term residual inoculum in debris.