Organization and evolution of resistance gene analogs in peanut |
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Authors: | Bayram Yuksel James C Estill Stefan R Schulze Andrew H Paterson |
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Institution: | (1) Plant Genome Mapping Laboratory, The University of Georgia, 111 Riverbend Road, Athens, GA 30605, USA |
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Abstract: | The scarcity of genetic polymorphism in Arachis hypogaea (peanut), as in other monophyletic polyploid species, makes it especially vulnerable to nematode, bacterial, fungal, and
viral pathogens. Although no disease resistance genes have been cloned from peanut itself, the conserved motifs in cloned
resistance genes from other plant species provide a means to isolate and analyze similar genes from peanut. To survey the
number, diversity, evolutionary history, and genomic organization of resistance gene-like sequences in peanut, we isolated
234 resistance gene analogs (RGAs) by using primers designed from conserved regions of different classes of resistance genes
including NBS-LRR, and LRR-TM classes. Phylogenetic and sequence analyses were performed to explore evolutionary relationships
both among peanut RGAs and with orthologous genes from other plant taxa. Fifty-six overgos designed from the RGA sequences
on the basis of their phyletic association were applied to a peanut BAC library; 736 hybridizing BAC clones were fingerprinted
and contigs were formed in order to gain insights into the genomic organization of these genes. All the fingerprinting gels
were blotted and screened with the respective overgos in order to verify the authenticity of the hits from initial screens,
and to explore the physical organization of these genes in terms of both copy number and distribution in the genome. As a
result, we identified 250 putative resistance gene loci. A correlation was found between the phyletic positions of the sequences
and their physical locations. The BACs isolated here will serve as a valuable resource for future applications, such as map-based
cloning, and will help improve our understanding of the evolution and organization of these genes in the peanut genome.
Electronic Supplementary Material Supplementary material is available for this article at . |
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Keywords: | Arachis hypogaea NBS-LRR Physical mapping TM-LRR RGA |
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