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: Akkaya, M.S., Chen, X., Bozkurt, O., Yildirim, F., Unver, T., Somel, M. 2004. Isolation of rgas and disease related gene fragments from wheat stripe rust resistant differential lines. 11th International Cereal Rusts and Mildews Conference European and Mediterranean Proceedings. Page A2.1.
Technical Abstract: Stripe (yellow) rust, caused by Puccinia striiformis f. sp. tritici, has been the most devastating wheat disease in Turkey and the region for the last 20 years. So far, only the sequence of Yr10 has been released as wheat stripe rust resistance gene against this biotrophic fungus (AF149114). We have used several methods for identification of genes involved in the resistance against stripe rust. Firstly, RGA fragments were investigated on Yr genes incorporated 17 differential Avocet lines (ICARDA and C. Wellings) conferring resistance against different strains of P. striiformis. Radioactively labeled PCR products using various RGA primers, corresponding to the p-loop, kinase and LRR domains, were separated on DNA denaturing gels. The fragments, each having a unique profile -present only in one Avocet-Yr line and absent in all the others including Avocet-S line were band isolated, cloned and sequenced. Our clone RGA1 shows 67% homology at protein level to a previously identified Rice Rim2 transcript which accumulates in response to infection with Magnoporthe grisea. Also predicted protein sequence of our clone RGA24 shows 46% homology to BIS1 protein of Hordeum vulgare which is up-regulated at the rust infection sites. Secondly, we have performed differential display (DD) method to identify those genes that are induced upon infection with races PST-17 and PST-45 of P. striiformis f. sp. tritici presenting compatible interactions with Avocet-Yr10 and Avocet-Yr1 lines, respectively. We have cloned and sequenced 6 DD bands from PST-17 infected/uninfected Avocet-Yr10 and 5 from PST-45 infected/uninfected Avocet-Yr1 samples by twelve DD primer combinations. Some of our clones show high degree of homology to receptor like kinases and PR proteins. Finally, we have used Yr differential lines to isolate Yr10 gene homologs. We have designed primers to amplify 1-1500 bp region of Yr10 which includes NBS and kinase domains. Expected size PCR products were sequenced from Avocet-Yr6 and Avocet-Yr11lines. Sequence analysis showed high degree of homology to the N-terminus of Yr10 gene. However, they were truncated. In addition to these fragments, a longer PCR product was obtained from both samples, showing homologies to 3' end of barley Rpg1 gene. The Avocet-Yr6 Rpg1 homolog had a deletion resulting stop codons. Yr10 homologs from other Avocet differential lines will be sequenced. Our findings in these three approaches will be presented.