Potential of Synthetic Hexapod Wheat for Stripe Rust Resistance in Ethiopia

Abstract

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 sub-
Saharan 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.