Molecular Characterization of the Ribosomal Protein L25 from the Stem Rust Fungus

Lin, K. C., Bushnell, W. R., and Szabo, L. J. 2004. Molecular characterization of the ribosomal protein L25 from the stem rust fungus. Plant Pathol. Bull. 13: 251-260. A cDNA clone (pCRL130) encoding a 25S rRNA-binding protein (L25) was isolated from the oat stem rust fungus, Puccinia graminis f. sp. avenae. The cDNA clone contains a 660 bp insert which encodes a putative polypeptide of 158 amino acids and is highly similar to those of eukaryotic ribosomal L25 proteins. Transcripts of the P. graminis L25 gene were detected as early as 48 h after host plants were inoculated with the fungus. Temporal patterns of transcript accumulation were closely correlated with fungal growth in host plants, giving more abundant transcript accumulation with compatible than with incompatible or inappropriate isolates of the fungus. Phylogenetic analysis of L23/L25 sequences divided the basidiomycetes into three well-supported lineages (Urediniomycetes, Hymenomycetes and Ustilaginomycetes) which is consistent with the current taxonomic division, based on ribosomal rDNA sequences. Similar results were obtained for taxonomic divisions among selected ascomycetes samples. This represents the first nonribosomal RNA gene analysis to confirm the division of basidiomycetes into three lineages and indicates that the L23/L25 amino acid sequence is a useful tool for studying fungal phylogenetics.