A NEW APPROACH FOR FINE MAPPING AND CLONING GENES FROM THE TERTIARY GENE POOL MEMBERS OF WHEAT: EXAMPLE OF LR57 FROM AEGILOPS GENICULATA

Abstract

Wheat is a staple food for 35% of the world’s population, providing more calories and protein to the world’s diet than any other crop. Wheat rust diseases cause yield losses worth billions of dollars annually. Two rust resistance genes, Lr57 and Yr40, conferring leaf rust and stripe rust resistance, respectively, were previously identified in a wild wheat relative, Aegilops geniculata. Mapping these genes within a wheat background is typically impossible, due to the absence of genetic recombination between wheat and wild species chromatin. We devised a novel technique to overcome this barrier, developing a mapping population from a cross between a resistant Ae. geniculata-wheat introgression line and a susceptible Ae. geniculata disomic addition line. Genotyping and phenotyping 162 individuals from this population, we found 11 recombinants within a 6 Mb interval and fine mapped Lr57, demonstrating the high-resolution power of this strategy for mapping genes from wild relatives of wheat.