title: Phylogenetic and evolutionary analysis of NBS-encoding genes in Rutaceae fruit crops.
abstract: The nucleotide-binding site leucine-rich repeat (NBS-LRR) genes are the largest class of disease resistance genes in plants. However, our understanding of the evolution of NBS-LRR genes in Rutaceae fruit crops is rather limited. We report an evolutionary study of 103 NBS-encoding genes isolated from Poncirus trifoliata (trifoliate orange), Citrus reticulata (tangerine) and their F(1) progeny. In all, 58 of the sequences contained a continuous open reading frame. Phylogenetic analysis classified the 58 NBS genes into nine clades, eight of which were genus specific. This was taken to imply that most of the ancestors of these NBS genes evolved after the genus split. The motif pattern of the 58 NBS-encoding genes was consistent with their phylogenetic profile. An extended phylogenetic analysis, incorporating citrus NBS genes from the public database, classified 95 citrus NBS genes into six clades, half of which were genus specific. RFLP analysis showed that citrus NBS-encoding genes have been evolving rapidly, and that they are unstable when passed through an intergeneric cross. Of 32 NBS-encoding genes tracked by gene-specific PCR, 24 showed segregation distortion among a set of 94 F(1) individuals. This study provides new insight into the evolution of Rutaceae NBS genes and their behaviour following an intergeneric cross.
authors.affiliation: National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, People's Republic of China. xuqiang@mail.hzau.edu.cn
authors.forename: Qiang
authors.initials: Q
authors.lastname: Xu
authors.forename: Manosh Kumar
authors.initials: MK
authors.lastname: Biswas
authors.forename: Hong
authors.initials: H
authors.lastname: Lan
authors.forename: Wenfang
authors.initials: W
authors.lastname: Zeng
authors.forename: Chaoyang
authors.initials: C
authors.lastname: Liu
authors.forename: Jidi
authors.initials: J
authors.lastname: Xu
authors.forename: Xiuxin
authors.initials: X
authors.lastname: Deng
mesh_terms: D000595:Amino Acid Sequence; D018556:Crops, Agricultural / Q000737:chemistry / Q000235:genetics*; D019143:Evolution, Molecular; D005638:Fruit / Q000737:chemistry / Q000235:genetics*; D000090263:Leucine-Rich Repeat Proteins; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics*; D011506:Proteins / Q000737:chemistry / Q000235:genetics*; D027821:Rutaceae / Q000737:chemistry / Q000235:genetics*; D016415:Sequence Alignment
chemical_list: D000090263:Leucine-Rich Repeat Proteins; D010940:Plant Proteins; D011506:Proteins