Vulnerability of Cultivated and Wild Barley to African Stem Rust Race TTKSK

Abstract

Stem rust is one of the most important diseases of wheat and barley worldwide. Highly virulent stem rust races such as TTKSK (aka isolate Ug99) from Africa represent one of the greatest threats to stable cereal production in 50 years, but little is known regarding the vulnerability of barley. This study was undertaken to determine the reaction of a large and diverse collection of cultivated and wild barley germplasm to race TTKSK at the seedling stage. Of the 1,902 cultivated barley accessions evaluated, only 43 (2.3%) consistently exhibited resistant to moderately resistant reactions across experiments. Similarly, only 16 (1.7%) of the 935 wild barley accessions consistently exhibited resistant to moderately resistant reactions. Pedigree analyses revealed that some of the resistant cultivated accessions were derived from the same parental sources. These results underscore the extreme vulnerability of barley to stem rust race TTKSK and the need to identify additional sources of resistance.