Abstract only

Pgt race TTKSK (Ug99) has a wide virulence range in respect to currently grown wheat cultivars worldwide. Aspects of migration, mutation, recombination and selection in the pathogen have led to previously deployed stem rust resistance genes being ineffective. Race TTKSK has further evolved to acquire virulence for resistance genes such as Sr24 (race Ug99+Sr24) and Sr36 (Ug99+Sr36). Five resistant wheat lines (KSL-1, KSL-2, KSL-3, KSL-4 and KSL-5) which were resistant in tests during 2008, 2009 and 2010 were used as parents in crosses with stem rust susceptible line Cacuke to develop genetic populations for determining the inheritance of resistance to stem rust. F3 populations were evaluated at KARI Njoro in the 2012 off-season nursery. The adult plant stem rust responses were scored using the modified Cobb scale. The F2:3 lines of population(s) exhibiting qualitative variation were grouped as homozygous resistant (HR), segregating (Seg) and homozygous susceptible (HS). Chi squared analysis was used to test the goodness of fit of observed and expected genetic ratios. Bulk segregant analysis (BSA) using SSR markers will be conducted to identify markers linked to the resistance genes. Populations exhibiting continuous phenotypic variation will be further analyzed by QTL analysis. The five resistant lines were also crossed in a partial diallel to estimate the general and specific combining abilities of each line. Superior transgressive segregants identified in the crosses will be used in breeding.

Global Wheat Program

English

Lucia Segura

INT2843

CIMMYT Staff Publications Collection