ARS | Publication request: STRUCTURAL EVOLUTION OF A RESISTANCE GENE ISLAND IN THE D GENOME OF WHEAT

Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: October 15, 2004
Publication Date: January 15, 2003
Citation: Brooks, S.A., Huang, L., Herbel, M., Gill, B.S., Brown Guedira, G.L., Fellers, J.P. 2003. Structural evolution of a resistance gene island in the D genome of wheat. Plant and Animal Genome Abstracts.

Technical Abstract: Chromosome rearrangements are common events that generate allelic diversity at disease resistance loci in wheat. Comparative analysis of structural diversity at resistance loci provides a means to determine the nature of events that drive resistance (R) gene evolution. Focusing on a cluster of genes related to disease resistance, located in the distal portion of chromosome 1DS of Aegilops tauschii, we observed varying degrees of haplotype and gene sequence conservation. Forty-two accessions were characterized for R gene content, and three representatives of specific haplotypes for sequence conservation. Five unique haplotypes were observed that are the result of various degrees of gene deletions. Our data fits a model for regional selective advantage of a specific haplotype, and buffering capacity for gene loss in diploid wheat relatives. Fitness costs may be associated with maintenance of the entire locus, preventing population fixation in the absence of pathogen pressure.