Global Diversity of Winter Wheat for Resistance to Stem Rust Race Ug99.

International Winter Wheat Improvement Program (www.iwwip.org) is a project established jointly in 1986 by the Ministry of Agriculture and Rural Affairs of Turkey, CIMMYT, and ICARDA. The objective of the program is to develop the facultative and winter wheat germplasm for the region of Central and West Asia. IWWIP also facilitates global germplasm exchanges for winter wheat by assembling lines from various sources, evaluating, and distributing selected entries through its system of international nurseries. Annually four different international nurseries are distributed globally to more than 120 cooperators in 50 countries. Breeding for resistance to rusts is a high priority along with adaptation and grain quality. Due to the emerging importance of stem rust race Ug99, evaluation of germplasm for stem rust resistance in Kenya started in 2008. From 2008 to 2010, approximately 2500 entries representing germplasm from all major winter wheat producing countries were evaluated at the Kenyan Agricultural Research Institute, Njoro. In each evaluation season, two ratings (10 days apart) on disease severity and infection responses were taken. Overall 300 entries have been selected for various degrees of stem rust resistance. Resistant germplasm was further tested with multiple stem rust races at the seedling stage in order to characterize the types of resistance and to postulate specific resistance genes. Germplasm resistant to Ug99 in Kenya was also tested in Turkey against local stem, yellow and leaf rust races. Performance of Ug99 resistant germplasm is presented.