|Liu, Zhaohui - PLNT PATH NDSU, FARGO ND|
|Meinhardt, Steven - BIO CHEM, NDSU, FARGO ND|
|Rasmussen, Jack - PLNT PATH NDSU, FARGO ND|
Submitted to: Plant and Animal Genome VX Conference Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 3, 2004
Publication Date: January 10, 2005
Citation: Liu, Z., Friesen, T.L., Meinhardt, S.W., Rasmussen, J.B., Faris, J.D. 2005. Mapping of toxin sensitivity and QTL analysis of seedling resistance to stagonospora nodorum blotch in an intervarietal hard red spring wheat population. Plant and Animal Genome Abstracts. p. 342. Technical Abstract: Stagonospora nodurum leaf blotch (SNB) is an economically important foliar disease in the major wheat growing areas of the world. Utilization of host resistance is considered to be the most important and preferred method to control disease. In related work, we identified a host-selective toxin (SnTox1) produced by the isolate Sn2000 and mapped the gene (Snn1) conditioning sensitivity to chromosome 1BS in the ITMI population. Here, we evaluated SnTox1 sensitivity and resistance to SNB caused by Sn2000 in a population of recombinant inbred (RI) lines derived from BR34 x Grandin. In this population, sensitivity to partially purified SnTox1 mapped to the long arm of chromosome 5B and cosegregated with Tsn1, which confers sensitivity to Ptr ToxA produced by the tan spot fungus. The tsn1 locus underlied a major QTL for resistance to SNB caused by Sn2000 and explained 58 percent of the phenotypic variation. Additional QTLs were identified on chromosomes 5AL and 6BS and explained 27 and 12 percent of the variation, respectively. These results indicate that toxins produced by different pathogens interact with a common host gene, or closely linked genes. Because SnTox1 cultures are only partially purified, they may contain more than one toxin, one of which interacts with Snn1 on 1BS and a second that recognizes Tsn1 or another closely linked gene. Nevertheless, a toxic component of isolate Sn2000 is a major virulence factor. Purification of SnTox1 is needed to determine if it recognizes Tsn1.