A diverse set of winter wheat germplasm was screened for resistance to stem rust in large-scale trials in Kenya and Turkey during 2009-16. The study aimed to select resistant material and characterize types of resistance and possible genes, as well as evaluate agronomic traits and resistance to other diseases to select superior variety candidates and parental lines. The study material was comprised of various Facultative and Winter Wheat Observation Nurseries (FAWWON), which are developed and distributed by the International Winter Wheat Improvement Program (www.iwwip.org) in Turkey. More than 1600 global accessions were screened, with most evaluated for two years. Based on stem rust data from Kenya, more than 400 genotypes were identified exhibiting adequate levels of resistance to the Ug99 race group. The highest number of resistant lines originated from IWWIP (~170), USA (~100), Russia (~40), Iran (~30), Romania (~20), and South Africa (~20). Material was also tested at two sites in Turkey: Haymana (artificial inoculation) and Kastamonu (natural infection). There was no significant correlation between stem rust severities in Kenya and in Turkey, due to differences in stem rust pathotypes. However, a set of germplasm (more than 100 entries) has been identified as resistant in both countries. This set represents promising material as variety candidates and parental lines; another study is currently identifying the genes controlling the stem rust resistance in this population. IWWIP distributed stem rust resistant germplasm to its global collaborators during 2010-2015, in response to the threat from the Ug99 race group. New resistant germplasm combining broad adaptation, high yields, and resistance to other diseases is available on request.
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Stem rust still remains an important threat to wheat with new races such as Ug99. In 2012 main season, some genotypes developed by Central Research Institute for Field Crops were sent to Kenya for screening to Ug99 and WWSRRN (winter wheat stem rust resistance nursery) was organized with resistant genotypes according to result. Addition to Ug99, the resistances to local stem rust, leaf rust and yellow rust races are important. The aim of this study was to determine reactions of 99 genotypes in WWSRRN to local rust population in the seedling stage (for PSt, Pgt and Pt) and adult plant stage (for Pst and Pgt) at the research facilities of CRIFC in Ankara and Kastamonu (stem rust) during 2014 season. For adult plant test; the genotypes were inoculated with local Pst populations (virulent on Yr2,6,7,8,9,25,27,Sd,Su,Avs) and local Pgt populations (avirulent on Sr24, Sr26, Sr27, and Sr31). Stripe and stem rust development on each entry were scored using the modified Cobb scale when the susceptible check Little Club had reached 80S infection severity in June and August 2014, respectively. Coefficients of infections were calculated and values below 20 were considered to be resistant. For seedling test; the seedling was inoculated with local Pgt, Pt (avirulent on Lr9, Lr19, Lr24, and Lr28) and Pst populations. Stripe, leaf and stem rust development on each entry were scored after 14 days with 0-4 and 0-9 scale for leaf-stem rust and yellow rust, respectively. Thirty seven (37%) (seedling) genotypes and 39 (39%) (adult stage) genotypes were resistant to local Pgt, 35 (35%) (seedling) were resistant to the local Pt, and 55 (56%) (seedling) and 59 (60%) (adult stage) genotypes were resistant to the local Pst populations. The resistance sources to stem, leaf, and stripe rust were determined with this research.