[Phylogenetic relationships and evolution of yeast-like symbionts of the small brown planthoppers based on partial 18S rDNA sequences].

The yeast-like symbionts are isolated and purified from the small brown planthoppers collected from five areas in China. The 18S rDNA sequences of them are determined. Combined with the sequences of other fungi, we have constructed a comprehensive phylogenetic tree. The results suggested that the taxonomic positions of the YLS are in the class Pyrenomycetes in the subphylum Ascomycotina and the YLS have the closest relationship with H. chrysospermus. The YLS of different areas in China and Japan may belong to different geographical populations of one species. We could also draw a conclusion that there are independent acquisitions of various symbionts in differentiated hosts.