Adult plant resistance of selected Kenyan wheat cultivars to leaf rust and stem rust diseases

Abstract

Phenotypic and genotypic evaluation of wheat genetic resources and development of segregating populations are pre-requisites for identifying rust resistance genes. The objectives of this study were to assess adult plant resistance (APR) of selected wheat genotypes to leaf rust and stem rust and to develop segregating populations for resistance breeding. Eight selected Kenyan cultivars with known resistance to stem rust, together with local checks were evaluated for leaf rust and stem rust resistance at seedling stage and also across several environments. Selected diagnostic markers were used to determine the presence of known genes. All eight cultivars were crossed with local checks using a bi-parental mating design. Seedling tests revealed that parents exhibited differential infection types against wheat rust races. Cultivars Paka and Popo consistently showed resistant infection types at seedling stage, while Gem, Romany, Pasa, Fahari, Kudu, Ngiri and Kariega varied for resistant and susceptible infection types depending on the pathogen race used. The control cultivars Morocco and McNair consistently showed susceptible infection types as expected. In the field, all cultivars except for Morocco showed moderate to high levels of resistance, indicating the presence of effective resistance genes. Using diagnostic markers, presence of Lr34 was confirmed in Gem, Fahari, Kudu, Ngiri and Kariega, while Sr2 was present in Gem, Romany, Paka and Kudu. Seedling resistance gene, Sr35, was only detected in cultivar Popo. Overall, the study developed 909 F 6:8 recombinant inbred lines (RILs) as part of the nested mating design and are useful genetic resources for further studies and for mapping wheat rust resistance genes.

Assessment of Fusarium head blight resistance in newly developed recombinant inbred lines of wheat

“…The FHB severity reaction of genotypes varied across the test environments given the variability in environmental conditions or differences in the aggressiveness of isolates. This was the observed trends across studied experimental sites with alternating wet and warmer environments of South Africa (Goswami and Kistler 2004;Figlan et al 2017). Cedara site had higher temperatures and humidity conditions (Table S1) compared to the Bethlehem site.…”

“…The Cedara site is a hotspot area of various plant diseases in South Africa. A recent study revealed a much higher disease pressure of leaf rust in Cedara, compared to other testing sites across the country (Figlan et al 2017).…”

Sources of Resistance to Stem Rust (Puccinia graminis f. sp. tritici) in Improved Durum Wheat (Triticum turgidum l.) Varieties of Ethiopia

“…Therefore, low disease development with high infection response on the tested cultivars in each location presenting evidence that the presence of partial resistance in addition to race specific resistance. In harmony with this Figlan, et al[41] reported of the tested Kenyan cultivar (Paka) carry the APR Sr2 gene with race specific resistance gene which exhibited resistance reaction at seedling stage but high infection response at adult stage.…”