Plant & Animal Genomes XI Conference

January 11-15, 2003
Town & Country Convention Center
San Diego, CA

Poster: Gene Isolation
            

CHARACTERIZATION OF THE BARLEY STEM RUST RESISTANCE GENE RPG1 FAMILY

¹ Department of Crop and Soil Sciences, Washington State University, Pullman, WA 99164-6420, USA

² Department of Crop and Soil Sciences and School of Molecular Biosciences, Washington State University, Pullman, WA 99164-6420, USA

The barley stem rust resistance gene Rpg1 encodes a protein with tandem protein kinase domains and homology to receptor-like kinases. Hybridization of 10 arrayed cDNA libraries representing 500,000 clones with an Rpg1 probe identified one very similar clone (ABC1037) and a more distantly related member of the gene family (ABC1036). Hybridization of the ABC1036 probe to the cDNA libraries identified two additional clones designated ABC1040 and ABC1041. A BLASTn search of the Barley EST database with the most diverged sequence (ABC1041) revealed another clone (ABC1063) closely related to ABC1041. Each of the Rpg1 gene family members was completely sequenced and mapped (except ABC1063 still in progress). ABC1037 and Rpg1 map to chromosome 1(7H) bin 01 about 50 kb apart and share 64% a.a. identity. ABC1036 and ABC1040 map to chromosome 7(5H) bin 07 and share 91% a.a. identity. The Rpg1/1037 and ABC1036/ABC1040 genes may represent recent duplication events. ABC1041 mapped very close to the stem rust resistance gene rpg4 on chromosome 7(5H) bin 13, but, based on high resolution mapping, it is not rpg4. ABC1063 has not been mapped due to lack of RFLP polymorphism but is similar to ABC1041 and share 65% a.a. identity. Genomic sequencing has revealed unusual exon organization and some very large introns. To date, no function has been assigned to any of these genes. Characterization of this gene family will provide insight into function and evolution of this novel resistance gene family in barley and other Triticeae.