Submitted to: Phytopathology
Publication Type: Abstract Only
Publication Acceptance Date: May 7, 1998
Publication Date: N/A
Technical Abstract: Resistance gene analogs (RGAs) from wheat were cloned using degenerate PCR primers based on conserved regions of previously cloned plant disease resistance genes. Restriction enzyme analysis tentatively separated 196 clones into 13 groups. Complete sequence analysis of 28 clones representing all 13 groups revealed four main classes; differences among classes were 25% or more. BLAST searches using wheat consensus sequences identified high similarity between the wheat RGAs and previously cloned RGAs from rice and barley, with some BLAST scores higher than 2000. All sequences with a BLAST score higher than 200 were retrieved and aligned with the four wheat consensus RGAs. Phylogenetic analysis of 18 sequences revealed that the wheat RGAs were more similar to RGAs from rice and barley than they were to each other; one of the wheat RGAs was 92% identical to a barley clone. Differences among the sequences were exploited to develop primers for converting each wheat RGA class into a Sequence Tagged Site. Experiments currently are underway to map the RGA sequences in the wheat genome and to determine whether any is linked to known resistance genes.