Plant & Animal Genome VI Conference

P28

ANALYSIS OF RESISTANCE GENE ANALOG cDNA CLONES FROM SOYBEAN

1. G313 Agronomy, Agronomy Department, Iowa State University, Ames, Iowa, 50011-1010
2. USDA-ARS/Agronomy Department, Iowa State University, Ames, Iowa, 50011-1010

Using class-specific probes for soybean disease Resistance Gene Analogs (RGAs) we screened Glycine max epitcotyl and root cDNA libraries. Our purpose was to determine if the RGAs were transcribed and to isolate their respective cDNA clones. We found differential expression between the two tissues, with four of the nine classes of RGAs detected in epicotyls and only one class detected in roots. Twelve cDNA clones, representing four classes of RGAs, were sequenced. Sequence analysis of the clones revealed that each clone was distinct except for containing many of the same domains found in L6 from flax, RPP5 from Arabidopsis and N from tobacco. These domains include the nucleotide binding site, the interleukin-1 resistance gene cytoplasmic domain and leucine rich repeats. These findings strengthen the idea that RGAs represent resistance genes.