Location: Crop Improvement and Protection ResearchTitle: Validation of rice blast resistance genes in barley using a QTL mapping population and near-isolines. Author
Submitted to: Journal of Breeding Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/15/2009
Publication Date: 12/21/2009
Citation: Kongprakhon, P., Cuesta-Marcos, A., Hayes, P.M., Richardson, K.L., Sirithunya, P., Sato, K., Steffenson, B., and Toojinda, T. 2009. Validation of rice blast resistance genes in barley using a QTL mapping population and near-isolines. Breeding Science. 59: 341-349. Interpretive Summary: Blast, caused by Pyricularia grisea, is a common disease in rice. This same pathogen can also cause disease in barley. Using barley mapping population, we determined that blast resistance in barley is located in an area that also confers resistance to barley stripe rust and mildew. We used barley near-isogenic lines that differ only at three rust QTL, including one for the region conferring blast resistance, to determine that the regions for stripe rust resistance and blast resistance are separate and not the same gene.
Technical Abstract: There are prior reports of Pyricularia grisea – the causal agent of blast of rice – causing disease in barley. In order to determine the specificity of this resistance in barley, we extended our previous mapping efforts to include blast isolates from barley and rice grown in Thailand and we assessed two resistance phenotypes: leaf blast (LB) and neck blast (NB). The largest-effect resistance QTL, on chromosome 1H, was associated with NB and LB and is located in a region rich in resistance genes, including QTL conferring resistance to stripe rust (incited by Puccinia striiformis fsp. hordei) and the mildew (Blumeria graminis) resistance gene Mla. The LB, NB, and mildew resistance alleles traces to one parent (Baronesse) whereas the stripe rust resistance allele traces to the other parent (BCD47) of the mapping population. Baronesse is the susceptible recurrent parent of a set of near-isogenic lines (NILs) for three stripe rust resistance QTL, including one on 1H. Unigene (EST) derived single nucleotide polymorphism haplotypes of these NILs were aligned with the blast mapping population QTL using Mla as an anchor. Baronesse and all NILs without the 1H introgression were resistant to LB and NB. However, two NILs with the 1H introgression were resistant to LB and NB. Both are resistant to stripe rust. Therefore, the QTL conferring resistance to stripe rust is separable by recombination from the blast resistance QTL.