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United States Department of Agriculture

Agricultural Research Service

Title: Families of Resistance Gene Analogs Are Conserved and Clustered

Authors
item Kanazin, V - ISU
item Marek, Laura - ISU
item Shoemaker, Randy

Submitted to: Proceedings of the National Academy of Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 27, 1996
Publication Date: N/A

Interpretive Summary: Several genes conferring resistance to plant diseases have been isolated from many different plant species. The details of their DNA sequences have been uncovered. Surprisingly, the hereditary material of these genes is very similar regardless of whether the genes confer resistance to a virus, a bacteria or a fungus, and regardless of the plant species. The authors used the conserved regions of cloned genes to isolate similar genes from soybean. They found that the genes were scattered across many chromosomes and that the chromosomal positions contained several copies of the genes. They also found that there are at least nine families of these genes and that some of the genes mapped very closely to known resistance genes. This work demonstrates that it may be possible to isolate and clone disease resistance genes in any plant based upon information provided from other genes from other species. This would allow for the cloning of resistance genes without the time and money expenditures currently required using existing procedures. This information will be most useful to plant geneticists and plant breeders.

Technical Abstract: Sequences of cloned resistance genes from a wide range of plant taxa reveal a striking similarity in sequence homology and structural motifs. This is observed among genes conferring resistance to viral, bacterial and fungal pathogens, as well as to an organophosphorous insecticide. In this study, oligonucleotide primers designed for conserved sequences from coding regions of N (tobacco), RPS2 (Arabidopsis) and L6 (flax) were used to amplify related sequences from soybean (Glycine max (L.) Merr.). Sequencing of amplification products indicated that at least nine families of resistance gene analogs (RGAs) were detected. Genetic mapping of members of these families located them to eight different linkage groups. Several RGA loci mapped near known resistance genes. A BAC library of soybean DNA was screened using primers and probes specific for five RGA families and clones were identified containing sequences unique to three families. Individual BACs contained two to six members of single RGA families. Clustering and sequence similarity of members of RGA families suggests a common process in their evolution. Our data indicate that it may be possible to use sequence homologies from conserved motifs of cloned resistance genes to identify candidate resistance loci from widely diverse plant taxa.

Last Modified: 10/1/2014
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