title: Evolutionary implications of intra- and interspecific molecular variability of pathogenesis-related proteins.
abstract: We have examined phylogenetic relationships in seven pathogenesis-related (PR) protein families. Within-family comparisons involved 79 species, 166 amino acid sequences, and 1,791 sites. For 37 species, 124 different PR isoforms were identified (an average of 3.3 per species). Thirty-one of the 37 species investigated tended to cluster together (84%). Of the 17 clusters distinguished in the seven phylogenetic trees, 10 (59%) were in agreement with their taxonomic status, ascertained at the family level. The strong similarities among the intraspecific forms, as compared to interspecific differences, argue for some kind of gene conversion, but the rare occurrence of widely different isoforms also suggests diversifying selection. PRs 1, 6, and 4 seem to be less differentiated than PRs 3, 2, 10, and 5.
authors.affiliation: Departamento de Genética, Instituto de Biociências, Universidade Federal do Rio Grande do Sul, C.P. 15053, CEP 91501-970, Porto Alegre, RS, Brazil. loreta.freitas@ufrgs.br
authors.forename: L B
authors.initials: LB
authors.lastname: Freitas
authors.forename: S L
authors.initials: SL
authors.lastname: Bonatto
authors.forename: F M
authors.initials: FM
authors.lastname: Salzano
mesh_terms: D000595:Amino Acid Sequence; D019143:Evolution, Molecular; D014644:Genetic Variation; D010802:Phylogeny; D010940:Plant Proteins / Q000145:classification / Q000235:genetics*
chemical_list: D010940:Plant Proteins; C053376:pathogenesis-related proteins, plant