Identification and characterization of NBS-LRR class resistance gene analogs in faba bean (Vicia faba L.) and chickpea (Cicer arietinum L.).
A PCR approach with degenerate primers designed from conserved NBS-LRR (nucleotide binding site-leucine-rich repeat) regions of known disease-resistance (R) genes was used to amplify and clone homologous sequences from 5 faba bean (Vicia faba) lines and 2 chickpea (Cicer arietinum) accessions. Sixty-nine sequenced clones showed homologies to various R genes deposited in the GenBank database. The presence of internal kinase-2 and kinase-3a motifs in all the sequences isolated confirm that these clones correspond to NBS-containing genes. Using an amino-acid sequence identity of 70% as a threshold value, the clones were grouped into 10 classes of resistance-gene analogs (RGA01 to RGA10). The number of clones per class varied from 1 to 30. RGA classes 1, 6, 8, and 9 were comprised solely of clones isolated from faba bean, whereas classes 2, 3, 4, 5, and 7 included only chickpea clones. RGA10, showing a within-class identity of 99%, was the only class consisting of both faba bean and chickpea clones. A phylogenetic tree, based on the deduced amino-acid sequences of 12 representative clones from the 10 RGA classes and the NBS domains of 6 known R genes (I2 and Prf from tomato, RPP13 from Arabidopsis, Gro1-4 from potato, N from tobacco, L6 from flax), clearly indicated the separation between TIR (Toll/interleukin-1 receptor homology: Gro1-4, L6, N, RGA05 to RGA10)- and non-TIR (I2, Prf, RPP13, RGA01 to RGA04)-type NBS-LRR sequences. The development of suitable polymorphic markers based on cloned RGA sequences to be used in genetic mapping will facilitate the assessment of their potential linkage relationships with disease-resistance genes in faba bean and chickpea. This work is the first to report on faba bean RGAs.
Palomino
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Departamento de Genética, E.T.S.I.A.M, Universidad de Córdoba, 14071 Córdoba, Spain. carmen.palomino.ext@juntadeandalucia.es
Satovic
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Cubero
J I
JI
Torres
A M
AM
D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D029863:Cicer / Q000235:genetics*; D017931:DNA Primers / Q000737:chemistry; D017343:Genes, Plant; D018745:Genome, Plant / Q000235:genetics; D007930:Leucine / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000378:metabolism; D010802:Phylogeny; D010935:Plant Diseases / Q000235:genetics*; D010940:Plant Proteins / Q000145:classification / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D020449:Repetitive Sequences, Amino Acid / Q000235:genetics; D016415:Sequence Alignment; D014157:Transcription Factors / Q000145:classification / Q000235:genetics*; D031307:Vicia faba / Q000235:genetics*
D017931:DNA Primers; D009711:Nucleotides; D010940:Plant Proteins; D014157:Transcription Factors; D007930:Leucine