title: Phylogenetic and evolutionary analysis of NBS-encoding genes in Rosaceae fruit crops.
abstract: Phylogenetic relationships of the nucleotide binding site (NBS)-encoding resistance gene homologues (RGHs) among 12 species in five genera of Rosaceae fruit crops were evaluated. A total of 228 Rosaceous RGHs were deeply separated into two distinct clades, designated as TIR (sequences within this clade containing a Toll Interleukin-1 Receptor domain) and NonTIR (sequences lacking a TIR domain). Most Rosaceous RGH genes were phylogenetically distinct from Arabidopsis, Rice or Pine genes, except for a few Rosaceous members which grouped closely with Arabidopsis genes. Within Rosaceae, sequences from multiple species were often phylogenetically clustered together, forming heterogenous groups, however, apple- and chestnut rose-specific groups really exist. Gene duplication followed by sequence divergence were proposed as the mode for the evolution of a large number of distantly or closely related RGH genes in Rosaceae, and this mode may play a role in the generation of new resistance specificity. Positively selected sites within NBS-coding region were detected and thus nucleotide variation within NBS domain may function in determining disease resistance specificity. This study also discusses the synteny of a genomic region that encompass powdery mildew resistance locus among Malus, Prunus and Rosa, which may have potential use for fruit tree disease breeding and important gene cloning.
authors: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, PR China.
authors: Qiang
authors: Q
authors: Xu
authors: Xiaopeng
authors: X
authors: Wen
authors: Xiuxin
authors: X
authors: Deng
mesh_terms: D001665:Binding Sites / Q000235:genetics; D030561:Databases, Nucleic Acid; D019143:Evolution, Molecular; D008957:Models, Genetic; D009711:Nucleotides / Q000378:metabolism*; D010802:Phylogeny; D027824:Rosaceae / Q000145:classification / Q000235:genetics*; D016415:Sequence Alignment
chemical_list: D009711:Nucleotides