Isolation, sequence analysis, and linkage mapping of resistance-gene analogs in cowpea (Vigna unguiculata L. Walp.) |
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Authors: | Bhavani S Gowda Jennifer L Miller Sarah S Rubin Dilram R Sharma Michael P Timko |
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Institution: | (1) Department of Biology, University of Virginia, Charlottesville, Virginia, 22903, U.S.A |
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Abstract: | Degenerate oligonucleotides designed to recognize conserved coding regions within the nucleotide binding site (NBS) and hydrophobic
region of known resistance (R)genes from various plant species were used to target PCR to amplify resistance gene analogs
(RGAs) from a cowpea (Vigna unguiculata L. Walp.) cultivar resistant to Striga gesnerioides. PCR products consisted of a group of fragments approximately 500 bp in length that migrated as a single band during agarose
gel electrophoresis. The nucleotide sequence of fifty different cloned fragments was determined and their predicted amino
acid sequences compared to each other and to the amino acid sequence encoded by known resistance genes, and RGAs from other
plant species. Cluster analysis identified five different classes of RGAs in cowpea. Gel blot analysis revealed that each
class recognized a different subset of loci in the cowpea genome. Several of the RGAs were associated with restriction fragment
length polymorphisms, which allowed them to be placed on the cowpea genomic map. The potential for using these sequences to
isolate R genes, and subsequent direct manipulation of disease and pest resistance using genetic engineering is discussed.
This revised version was published online in August 2006 with corrections to the Cover Date. |
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Keywords: | cowpea disease and pestresistance molecular cloning resistancegene analogs Striga |
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