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POSTERS: Population biology and genetics

Virulence diversity of Puccinia graminis f. sp. tritici in Ethiopia
Endale Hailu - Ethiopian Institute of Agricultural Research. Tsegeab Tesfaye- Ethiopian institute of Agricultural Research, Kitessa Gutu- Ethiopian Institute of Agricultural Research, Worku Denbel- Department of Plant Pathology, University of Minnesota, Yue Jin- USDA-ARS Cereal Disease Laboratory, Netsanet Bacha- E

Stem rust caused by Puccinia graminis f. sp. tritici (Pgt) is a major production constraint in most wheat growing areas of Ethiopia. In 2013 a severe local epidemic caused by race TKTTF resulted in devastating losses to wheat growers in the main wheat growing regions of Bale and Arsi. The present study was conducted to investigate the virulence composition and diversity of Pgt in Ethiopia after the TKTTF epidemic. Stem rust samples collected from the major wheat growing areas in Ethiopia were race-typed at both the Ambo Plant Protection Center in Ethiopia and the USDA Cereal Disease Laboratory in Minnesota. More than 24 Pgt races were identified since the stem rust epidemic in 2013. Pgt races TKTTF, TTKSK, TTTTF, JRCQC, and RRTTF were widely distributed and have been identified almost at each cropping season. Although race TKTTF has been the predominant race in all survey years, its frequency has been declining as newly emerged races, such as TTRTF and TKKTF, are becoming more prevalent in the last two years. Two races with Sr24 virulence were identified in 2016 (TKFTP) and 2017 (TTKST). This virulence is significant because several major cultivars rely on Sr24 for stem rust resistance. The majority of the identified races are virulent to most of the wheat cultivars currently grown in the country. The continuous emergence of new virulent races in Ethiopia underlines the need for monitoring the pathogen population and identifying effective resistance genes that can be used in the national wheat-breeding program to control this devastating disease.