|Bowden, Robert - Bob|
Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/22/2007
Publication Date: 1/1/2008
Citation: Singh, S., Bockus, W., Sharma, I., Bowden, R.L. 2008. A novel source of resistance in wheat to pyrenophora tritici-repentis race 1. Plant Disease. 92:91-95. Interpretive Summary: Tan spot is a foliar disease that causes serious yield losses in wheat and many other grasses. Genetic resistance to tan spot has been successful, but new sources of resistance are needed to achieve higher levels of disease control. A mapping population from the cross between the Indian spring wheats WH542 (resistant) and HD29 (moderately-susceptible) was evaluated for reaction to the disease. Genes for resistance were detected on chromosome 3A explaining 23% of the variation, and on chromosome 5B explaining 27% of the variation for resistance. Both resistance genes were contributed by the WH542 parent. The gene on 5B is probably tsn1, which was described previously. The gene on 3A is a novel gene for resistance to tan spot. Markers were found that are suitable for marker-assisted selection for tan spot resistance.
Technical Abstract: Tan spot, caused by the fungus Pyrenophora tritici-repentis, causes serious yield losses in wheat (Triticum aestivum) and many other grasses. Race 1 of the fungus, which produces the necrosis toxin Ptr ToxA and the chlorosis toxin Ptr ToxC, is the most prevalent race in the Great Plains of the USA. Wheat genotypes with useful levels of resistance to race 1 have been deployed, but this resistance only reduces damage by 50-75%. Therefore, new sources of resistance to P. tritici-repentis are needed. Recombinant inbred lines developed from a cross between the Indian spring wheats WH542 (resistant) and HD29 (moderately-susceptible) were evaluated for reaction to race 1 of the fungus. Composite interval mapping revealed quantitative trait loci (QTL) on the short arm of chromosome 3A explaining 23% of the phenotypic variation, and the long arm of chromosome 5B explaining 27% of the variation. Both resistance alleles were contributed by the WH542 parent. The QTL on 5BL is probably tsn1, which was described previously. The 3AS QTL (QTs.ksu-3AS) on 3AS is a novel QTL for resistance to P. tritici-repentis, race 1. The QTL region is located in the most distal bin of chromosome 3AS in a 2.2 cM marker interval. Flanking markers Xbarc45 and Xbarc86 are suitable for marker-assisted selection for tan spot resistance.