Potential of Synthetic Hexapod Wheat for Stripe Rust Resistance in Ethiopia

Stripe rust caused by Puccinia striiformis f.sp. tritici is one of the major constraints of wheat production worldwide. The most recent epidemics was occurred in 2010 in major wheat growing regions of central, west Asia, north and subSaharan Africa causing significant yield losses because of breakdown of resistance in predominantly cultivated wheat varieties (e.g. Kubsa/Attila and Galama in Ethiopia and Cham-8 in Syria). The major cause might be the narrow genetic base on which the breeding for resistance has been founded. Many control measures have been used to minimize the losses incurred by yellow rust but use of resistant cultivars remains the most economical, efficient and environment and farmer friendly strategy. To broaden the genetic basis of wheat cultivars, it is important to collect, evaluate and document new source of resistance genes from wild relatives of wheat including Triticum and Aegilops species. Synthetic hexaploid wheat (SHW) is a valuable genetic resource for resistance to a range of biotic stresses. A total of 653 SHWs derived from Aegilops tauschii and Triticum turgidum subsp. durum were evaluated for resistance to yellow rust in Meraro and Kulumsa, Ethiopia, at the adult plant growth stage. Of these, 644 entries were further tested on wheat cultivars carrying Yr2, Yr6, Yr7, Yr9, YrA, Yr25 and Yr27 against stripe rust isolates virulent on these genes at the seedling growth stage of 116 exhibited resistant to moderately resistant reaction under field conditions in both locations. Of these, 40 and 76 SHWs showed susceptible and resistant reactions at the seedling stage, respectively. The resistant SHWs identified could be useful in broadening the genetic bases of stripe resistance and further characterized to uncover potentially new resistance gene(s) in SHWs effective against prevalent races currently attacking wheat in Ethiopia and other stripe rust countries in the region.