Common or bread wheat (Triticum aestivum L.) is the most important cereal crop in the world, including Kazakhstan, where it is a major agricultural commodity. Fungal pathogens producing leaf, stem, and yellow (stripe) rusts of wheat may cause yield losses of up to 50–60%. One of the most effective methods for preventing these losses is to develop resistant cultivars with high yield potential. This goal can be achieved using complex breeding studies, including the identification of key genetic factors controlling rust disease resistance. In this study, a panel consisting of 215 common wheat cultivars and breeding lines from Kazakhstan, Russia, Europe, USA, Canada, Mexico, and Australia, with a wide range of resistance to leaf rust (LR), stem rust (SR), and yellow rust (YR) diseases, was analyzed under field conditions in Southern Kazakhstan. The collection was genotyped using the 20K Illumina iSelect DNA array, where 11,510 informative single-nucleotide polymorphism markers were selected for further genome-wide association study (GWAS). Evaluation of the phenotypic diversity over 2 years showed a mostly mixed reaction to LR, mixed reaction/moderate susceptibility to SR, and moderate resistance to YR among wheat accessions from Kazakhstan. GWAS revealed 45 marker–trait associations (MTAs), including 23 for LR, 14 for SR, and eight for YR resistances. Three MTAs for LR resistance and one for SR resistance appeared to be novel. The MTAs identified in this work can be used for marker-assisted selection of common wheat in Kazakhstan in breeding new cultivars resistant to LR, SR, and YR diseases. These findings can be helpful for pyramiding genes with favorable alleles in promising cultivars and lines.

Severe epidemics of wheat stem rust caused by Puccinia graminis f. sp. tritici (Pgt) have been observed in recent years in major spring wheat producing regions in Kazakhstan. However, information on the virulence structure and race composition of Pgt is currently not available. Stem rust samples were collected in 2015–2018 in three regions of Kazakhstan to determine the virulence diversity and race distribution in the Pgt populations. A total of 203 single-pustule isolates were derived and evaluated on the stem rust differential and supplemental lines and 38 races were identified. Among them, the races QHHSF and THMTF were found in all the regions and in all the years. The races RFRTF, RHMRF, TKRPF and MHCTC were the most common races in the Akmola and Kostanay regions, and the races LHCSF, QKCSF and LKCSF were only widely distributed in East Kazakhstan. The virulence complexity (i.e., number of Sr genes on which the races were virulent) ranged from 5 to 16, with about 40% of the races having 14 or more virulence. The stem rust resistance genes Sr11, Sr13, Sr22, Sr26, Sr31, Sr33 and Sr35 were found to confer resistance to all the races identified during the study period. Hence, these genes can be used as sources of resistance in wheat breeding programmes in Kazakhstan.

BackgroundPowdery mildew of barley is a wind-borne and obligate biotrophic pathogen, which ranks among the most widespread barley pathogens worldwide. However, purposeful research towards studying the structure of the barley powdery mildew populations, of their virulence and of effectiveness of certain resistance genes against the infection was not conducted in Kazakhstan till present time. This paper is the first to describe characteristics of the pathotype structure of Blumeria graminis f.sp. hordei (Bgh) population and effectiveness of resistance genes in two regions of barley cultivation in the republic.ResultsOne hundred and seven isolates of Bgh were obtained from seven populations occurring on cultivated barley at two geographically locations in Kazakhstan during 2015 and 2016. Their virulence frequency was determined on 17 differential lines Pallas. All isolates were virulent on the resistance gene Mla8 and avirulent for the resistance genes Mla9, Mla1 + MlaAl2, Mla6 + Mla14, Mla13 + MlRu3, Mla7 + MlNo3, Mla10 + MlDu2, Mla13 + MlRu3 and Mlo-5. The frequencies of isolates overcoming the genes Mla3, Mla22, Mlat Mlg + MlCP and Mla12 + MlEm2 were 0.0–33.33%, and frequencies of isolates overcoming the genes Mlra, Mlk, MlLa and Mlh ranged from 10.0 to 78.6%. Based on reactions of differential lines possessing the genes Mla22, Mlra, Mlk, Mlat, MlLa and Mlh, pathotypes were identified. In total, 23 pathotypes with virulence complexity ranging from 1 to 6 were identified. During both years in all populations of South Kazakhstan and Zhambyl regions pathotypes 24 and 64 mainly prevailed.ConclusionsObtained data suggest that low similarity of populations Bgh in Kazakhstan to European, African, Australian and South-East Asian populations. The present study provides a foundation for future studies on the pathogenic variability within of Bgh populations in Kazakhstan and addresses the knowledge gap on the virulence structure of Bgh in Central Asia. Complete effectiveness of the resistance genes, for which no corresponding virulence was found, will allow Kazakhstanean breeders to access many modern barley cultivars that those possessing the resistance effectiveness genes.

Leaf rust caused by Puccinia triticina Erikss. is a harmful disease of spring soft wheat in Russia and Kazakhstan. For higher effectiveness of selection programs, Kazakhstan-Siberian Network for Wheat Improvement (KASIB) including the leading institutions of Kazakhstan and Siberia was established. Integrated ecological studies of selection material including those on leaf rust resistance are conducted under the KASIB programs. The work goal is to identify leaf rust resistance genes using the plant pathology and molecular approaches. Forty seven samples of spring soft wheat are included in KASIB program for 2019-2020. Virulence-labeled clones and geographically distant populations of P. triticina were used for plant pathology testing in seedling phase, and 11 wheat samples with high level of rust resistance at seedling phase were found. Identification of target 21 Lr-genes has been performed using molecular markers with positive result in 82 % of the studied samples. Wheat samples highly resistant in the seedling phase demonstrated Lr24-gene alone or in combination with partially effective genes Lr26 and Lr9, as well as genes LrSp and Lr6Agi1, not identical to the known effective genes; as well as effective combinations of genes: Lr19+Lr26; Lr9+Lr26 and Lr19+Lr26+Lr41. The resistance genes Lr34 and Lr37 of adult plants have been detected in 8 % of the lines. In samples susceptible at seedling phase, low efficacy genes Lr1, Lr3, Lr10 are frequent. The screening has demonstrated high Lr-genes diversity of the spring wheat collection and considerable progress in wheat selection for the leaf rust resistance in Russia and Kazakhstan.

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