The objective of this study was to characterize seedling and adult plant resistance to all three rusts in a set of 40 bread wheat varieties currently cultivated in Tajikistan. Gene postulation based on multi-pathotype seedling test data and adult plant responses identified Yr2, Yr9, Yr17 and Yr27; Lr10 and Lr26; and Sr5, Sr6, Sr10, Sr11, Sr31 and Sr38. The effects of slow rusting, adult plant, pleiotropic resistance genes Lr34/Yr18/Sr57 and Yr30/Lr27/Sr2 were observed in the field and confirmed with molecular markers. Furthermore, molecular markers diagnostic for Yr9/Lr26/Sr31 and Yr17/Lr37/Sr38 were assessed on all varieties. Genes Lr34/Yr18/Sr57, Yr9/Lr26/Sr31 and Yr27 were identified in varieties Sarvar, Vahdat, Oriyon, Isfara, Ormon, Alex, Sadokat, Ziroat-70, Iqbol, Shokiri, and Safedaki Ishkoshimi based on phenotypic and genotypic results. Some lines were highly resistant to stripe rust (4 varieties), leaf rust (5) and stem rust (9), but the genes responsible could not be identified. They may possess new resistance genes. We thus identified combinations of major and minor rust resistance genes in Tajik wheat varieties. These varieties can now be used by breeders in Tajikistan as crossing parents to develop new varieties with durable resistance to the rusts.
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Wheat farmers in Tajikistan measure their success by harvesting higher grain yields. However, crop yields remain very low, and losses from pests and diseases are significant. In this regard, continuous monitoring and surveillance of crops for pests and diseases and identification of resistant varieties are important. During 2011 to 2014 FAO and CIMMYT provided support for crop surveillance to obtain an overview of the most severe diseases, insects, weeds and other constraints affecting cereal crop production. Leading Tajik wheat varieties were screened for resistance to major diseases under controlled conditions in Turkey. The outcomes of the surveys demonstrated that the most devastating leaf diseases of wheat in Tajikistan are yellow rust, leaf rust and occasionally stem rust. Yellow rust was present during spike formation and flowering in most wheat growing areas. Leaf rust developed later in the season and did not significantly affect yield. In 2013 yellow rust reached epidemic levels, especially in central and central-eastern parts of the country. Stem rust was occasionally observed at moderate levels in highland spring wheat areas (above 1,000 masl). Only three varieties screened in Turkey showed resistance to yellow rust; these included Ormon and Alex that originated from CIMMYT materials. However, the majority of currently grown varieties were susceptible. Seventeen of 43 varieties were resistant or displayed only trace levels of leaf rust. Wheat crops are also damaged by powdery mildew, tan spot, Septoria leaf blotch and seed-borne diseases such as common bunt and loose smut.