Virtual Graduation Ceremony

44th Graduation Ceremony

PhD in PLANT BREEDING


Host Plant Resistance in Wheat (Triticum Aestivum L.) Genotypes to Stripe Rust (Puccinia Striiformis Westend. F. Sp. Tritici Eriks) and Race Analysis in Kenya

Abstract: Yellow rust (Puccinia striiformis f. sp. tritici) (Pst), is one of the major foliar diseases causing significant yield losses in wheat worldwide. Objectives of this study were to: (i) characterize stripe rust races in Kenya using differential sets and molecular markers, (ii) determine stripe rust resistance genes among wheat cultivars for seedling and adult plant resistance and (iii) determine resistant alleles of wheat fungal diseases resistance in Kenyan genotypes using Kompetitive allele specific PCR (KASP) markers. In the first experiment, 50 stripe rust isolates collected between 1970 – 1992 and 2009 -2014 were characterized using stripe rust differential sets at seedling stage and species-specific sequence-characterized-amplified-region (SCAR) markers. In the second experiment, 12 Kenyan wheat varieties and 8 Watkin landraces, were evaluated at seedling and adult plant stage to identify resistant genotypes to Pst. The host reaction and rust severity In the third experiment, 98 Kenyan wheat genotypes were genotyped using 12 KASP assays to determine resistant alleles for wheat Pst. In this study, 14 races were virulent to Pst genes Yr1, Yr2, Yr3, Yr6, Yr7, Yr8, Yr9, Yr17, Yr25, Yr27 and YrAvS. Among the 14 races, 10 were detected in Pst samples obtained from 1970 to 1992 and 3 additional races were detected from 2009 to 2014 while 1 race detected in both periods. Race DK02d/12 from Denmark was more virulent on the genotypes than any other race and genotype K. Tai was resistant to this race with infection types “0” to “3”. In the field, there was differential response of genotypes to Pst infection across the 3 environments. Varieties, K. Korongo, K. Hawk12, K. Sunbird exhibited disease reaction of 20MR and 20MS, while genotypes 1190026, 1190826, 1190120 and 1190524 exhibited disease reaction ranging from 50- 80S. The resistant alleles for Yr5, Yr15 were at a low frequency, while Sr22 and Sr26 were absent in the Kenyan wheat genotypes. Cultivars K. Wren and R. Sabanero were resistant to stem rust (Sr2) leaf rust (Lr34). Cultivars K. Tai and K. Wren R. Sabanero with resistant alleles for Sr2 and Lr34 can be exploited in wheat breeding programmes for cultivar improvement.

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Egerton University
P.O Box 536-20115, Egerton, Kenya

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Email: raca@egerton.ac.ke

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