Resistance to race TKTTF of Puccinia graminis f. sp. tritici with virulence to SrTmp gene in Ethiopian bread wheat lines
Puccinia graminis f. sp. tritici (Pgt) is the major wheat production constraint in Ethiopia causing recurrent epidemics that resulted in the withdrawal of widely grown wheat cultivars from production. Among the current Pgt races detected in Ethiopia, TKTTF is the most frequent and has caused a severe epidemic in the south wheat growing regions (Bale and Arsi) after its first detection in 2012. Therefore, to avert the current situation, identifying sources of resistance to race TKTTF in breeding germplasm is a top priority to the National Wheat Breeding Program. Hence, 82 promising bread wheat lines including five check cultivars were evaluated in Debre Zeit in a TKTTF single race nursery for three consecutive seasons, 2014-2016. Ethiopian bread wheat cultivar Digalu was used as a spreader row and was inoculated using a single isolate of race TKTTF at different growth stages. The nursery was bounded by oat to reduce interference with any other stem rust race. The 82 lines were tested in the greenhouse at Cereal Disease Laboratory and were also tested with known diagnostic molecular markers. Twenty-nine lines displayed low levels of terminal stem rust severity in the field and low coefficient of infections. Fourty-one lines were resistant to race TKTTF at the seedling stage. Bread wheat lines resistant to TKTTF are valuable sources of resistance that can be deployed in wheat growing regions of Ethiopia prone to stem rust.