Comparative genetics of nucleotide binding site-leucine rich repeat resistance gene homologues in the genomes of two dicotyledons: tomato and arabidopsis.
The presence of a single resistance (R) gene allele can determine plant disease resistance. The protein products of such genes may act as receptors that specifically interact with pathogen-derived factors. Most functionally defined R-genes are of the nucleotide binding site-leucine rich repeat (NBS-LRR) supergene family and are present as large multigene families. The specificity of R-gene interactions together with the robustness of plant-pathogen interactions raises the question of their gene number and diversity in the genome. Genomic sequences from tomato showing significant homology to genes conferring race-specific resistance to pathogens were identified by systematically "scanning" the genome using a variety of primer pairs based on ubiquitous NBS motifs. Over 70 sequences were isolated and 10% are putative pseudogenes. Mapping of the amplified sequences on the tomato genetic map revealed their organization as mixed clusters of R-gene homologues that showed in many cases linkage to genetically characterized tomato resistance loci. Interspecific examination within Lycopersicon showed the existence of a null allele. Consideration of the tomato and potato comparative genetic maps unveiled conserved syntenic positions of R-gene homologues. Phylogenetic clustering of R-gene homologues within tomato and other Solanaceae family members was observed but not with R-gene homologues from Arabidopsis thaliana. Our data indicate remarkably rapid evolution of R-gene homologues during diversification of plant families.
Pan
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Department of Plant Science, Weizmann Institute of Science, Rehovot 76100, Israel.
Liu
Y S
YS
Budai-Hadrian
O
O
Sela
M
M
Carmel-Goren
L
L
Zamir
D
D
Fluhr
R
R
D000483:Alleles; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D001665:Binding Sites; D002874:Chromosome Mapping; D017343:Genes, Plant; D018745:Genome, Plant; D000090263:Leucine-Rich Repeat Proteins; D018551:Solanum lycopersicum / Q000235:genetics*; D008969:Molecular Sequence Data; D005810:Multigene Family; D009711:Nucleotides; D010802:Phylogeny; D010935:Plant Diseases / Q000235:genetics; D010940:Plant Proteins / Q000235:genetics*; D011506:Proteins / Q000235:genetics; D011544:Pseudogenes; D017386:Sequence Homology, Amino Acid; D019657:Solanaceae / Q000235:genetics
D000090263:Leucine-Rich Repeat Proteins; D009711:Nucleotides; D010940:Plant Proteins; D011506:Proteins