ARS | Publication request: Virulence characterization of international collections of the wheat stripe rust pathogen, Puccinia striiformis f. sp. tritici

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 4, 2012
Publication Date: October 18, 2012
Citation: Sharma-Poudyal, D., Chen, X., Wan, A., Zhan, G., Kang, Z., Cao, S., Jin, S., Morgounov, A.Q., Akin, B.Q., Mert, Z., Shah, S.Q., Bux, H.Q., Ashraf, M.Q., Sharma, R.Q., Madariaga, R.Q., Puri, K., Wellings, C., Xi, K.Q., Wanyera, R., Manninger, K., Ganzalez, M.Q., Koyda, M.Q., Sanin, S.Q., Patzek, L.Q. 2012. Virulence characterization of international collections of the wheat stripe rust pathogen, Puccinia striiformis f. sp. tritici. Plant Disease. 97:379-386.

Interpretive Summary: Wheat stripe rust is an economically important disease of wheat worldwide. Virulence information of the pathogen populations is important to implement effective disease control with resistant cultivars. A total of 235 Pst isolates from Algeria, Australia, Canada, Chile, China, Hungary, Kenya, Nepal, Pakistan, Russia, Spain, Turkey, and Uzbekistan were tested on 20 single stripe rust resistance gene lines and the 20 wheat genotypes that are used to differentiate races of the wheat stripe rust pathogen in the U.S. The 235 isolates were identified as 114 races on the single-gene lines and 160 races on the U.S. differentials. Virulences to 13 individual resistance genes and 12 wheat differential cultivars (each with one to three resistance genes) were detected in all countries. At least 80% of the isolates were virulent on 10 single gene lines and 5 U.S. differential cultivars . Virulences to 4 single-gene lines and 10 U.S. differential cultivars were moderately frequent (>20 - <80%). Virulence to 4 single-gene lines and differential cultivar Moro were low (=20%). Unique and common virulences, as well as avirulences, were identified in the rust collections in these countries. Although the frequencies of virulence factors were different, most of the isolates from these countries shared common virulence factors. The results are useful in understanding the virulence distributions, changes, and migrations of the pathogen and using effective resistance genes in breeding programs in the world.

Technical Abstract: Wheat stripe rust (yellow rust, Yr), caused by Puccinia striiformis f. sp. tritici (Pst), is an economically important disease of wheat worldwide. Virulence information of Pst populations is important to implement effective disease control with resistant cultivars. A total of 235 Pst isolates from Algeria, Australia, Canada, Chile, China, Hungary, Kenya, Nepal, Pakistan, Russia, Spain, Turkey, and Uzbekistan were tested on 20 single Yr-gene lines and the 20 wheat genotypes that are used to differentiate Pst races in the U.S. The 235 isolates were identified as 114 races on the single-gene lines and 160 races on the U.S. differentials. Virulences to YrA, Yr2, Yr6, Yr7, Yr8, Yr9, Yr17, Yr25, YrUkn, Yr27, Yr28, Yr31, YrExp2, Lemhi (Yr21), Paha (YrPa1, YrPa2, YrPa3), Druchamp (Yr3a, YrD, YrDru), Produra (YrPr1, YrPr2), Stephens (Yr3a, YrS, YrSte), Lee (Yr7, Yr22, Yr23), Fielder (Yr6, Yr20), Tyee (YrTye), Tres (YrTr1, YrTr2), Express (YrExp1, YrExp2), Clement (Yr9, YrCle), and Compair (Yr8, Yr19) were detected in all countries. At least 80% of the isolates were virulent on YrA, Yr2, Yr6, Yr7, Yr8, Yr17, YrUkn, Yr28, Yr31, YrExp2, Yr21, Produra (YrPr1, YrPr2), Stephens (Yr3a, YrS, YrSte), Lee (Yr7, Yr22, Yr23), and Fielder (Yr6, Yr20). Virulences to Yr1, Yr9, Yr25, Yr27, Heines VII (Yr2, YrHVII), Paha (YrPa1, YrPa2, YrPa3), Druchamp (Yr3a, YrD, YrDru), Yamhill (Yr2, Yr4a, YrYam), Tyee (YrTye), Tres (YrTr1, YrTr2), Hyak (Yr17, YrTye), Express (YrExp1, YrExp2), Clement (Yr9, YrCle), and Compair (Yr8, Yr19) were moderately frequent (>20 - <80%). Virulence to Yr10, Yr24, Yr32, YrSP, and Moro (Yr10, YrMor) were low (=20%). Virulence to Moro was absent in Algeria, Australia, Canada, Russia, Spain, Turkey, and China, but 10% of the Chinese isolates were virulent to Yr10. None of the isolates from Canada, China, and Kenya were virulent to Yr24; none of the isolates from Algeria, Australia, Canada, Nepal, Russia, and Spain were virulent to Yr32; none of the isolates from Australia, Canada, Chile, Hungary, Kenya, Nepal, Pakistan, Russia, and Spain were virulent to YrSP; and none of the isolates from all countries were virulent to Yr5 and Yr15. Although the frequencies of virulence factors were different, most of the Pst isolates from these countries shared common virulence factors.