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item Chen, Xianming

Submitted to: Cereal Rusts and Mildews Conference European and Mediterranean Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/2004
Publication Date: 7/1/2004
Citation: Chen, X., Pahalawatta, V. 2004. Genetics and molecular mapping of resistance genes in wheat and barley against inappropriate formae speciales of puccinia striiformis. 11th International Cereal Rusts and Mildews Conference European and Mediterranean Proceedings. Page A2.9.

Interpretive Summary:

Technical Abstract: Most wheat varieties are resistant to barley stripe rust caused by Puccinia striiformis f. sp. hordei (PSH) and most barley varieties are resistant to wheat stripe rust caused by P. striiformis f. sp. tritici (PST) (Chen et al., 1995b). The wheat variety Lemhi, which is susceptible to all PST (previously called CDL for Cereal Disease Laboratory) races except for PST-21, is resistant to all tested PSH races. Similarly, the barley variety Steptoe, which is susceptible to all PSH races, is resistant to all tested PST races. To determine genetics of the Lemhi resistance to PSH and the Steptoe resistance to PST, crosses were made between Lemhi and PI 478214, a wheat genotype originally from Ethiopia and susceptible to all tested PST and PSH races, and between Steptoe and Russell, a barley variety susceptible to some PST races and all tested PSH races. Seedlings of parents and F1, BC1, F2, and F3 progeny from the wheat cross were tested with races PSH-14, PSH-48, and PST-21, and those from the barley cross were tested with races PST-41 and PST-45 under controlled greenhouse conditions. Genetic analyses of infection type data showed that Lemhi had a dominant gene (provisionally designated as RpsLem) for resistance to the PSH races and the gene was closely linked to Yr21, a previously reported gene for resistance to PST-21 (Chen et al. 1995a); and that Steptoe had a dominant gene and a recessive gene (provisionally designated as YrStep1 and yrStep2, respectively) for resistance to races PST-41 and PST-45. For each of the crosses, genomic DNA was extracted from the parents and 150 F2 plants that were tested for rust reaction and which produced the F3 progeny that were tested with the races to confirm the phenotypes and determine the homozygosity/heterozygosity of the F2 plants. The phenotypic data and polymorphic markers identified using the resistance gene analog polymorphism (RGAP) technique (Chen et al. 1998a; 1998b) were analyzed with the Mapmaker computer program (Lander et al., 1987) to map the resistance genes. A linkage group for the genes in Lemhi was constructed with 11 RGAP markers and a linkage group for the dominant gene in Steptoe for resistance to PST was constructed with 12 RGAP markers. Using an RGAP marker that was linked to the resistant allele in repulsion and the set of nulli-tetrasomic Chinese Spring lines, the linkage group for RpsLem and Yr21 was mapped on wheat chromosome 1B, which confirmed the chromosomal location of Yr21 (Chen et al. 1995a). The results show that resistance in wheat and barley to inappropriate stripe rust pathogens is qualitatively inherited. These genes may provide effective resistance against appropriate pathogens when introgressed into appropriate hosts from inappropriate hosts.