2.2.6. Sixth stage

Sr47 genes were rare, with a frequency of 4.4 and 1.4%, respectively. After PCR analysis, 137 individual plants with several Sr genes in the homozygous state were selected from 200 spring plants, namely: with two resistance genes—54 plants, with three—64 plants, with four—15

In individual winter plants, selected from the hybrid population represented by the families F3, BC1F2, BC1F3, BC2F3, BC3F2 of different origin, eight genes were identified, which form a row: Sr2 > Sr44 > Sr32 > Sr36 > Sr22 > Sr31 > Sr47 > Sr39 and Sr40 by the frequency of occurrence in progeny. The combination spectrum of the identified genes in winter wheat plants differed from the spectrum of genes identified in spring wheat lines. This is connected with the orientation of backcrossings conducted in winter and spring wheat. The combination of Sr genes compound in the genotypes of winter wheat is more diverse. The plants with the combination of the Sr22, Sr32 and Sr44 genes in the homozygous state were most often encountered. Plants with a unique combination of genes characteristic only of winter plants have been found: Sr2 + Sr22, Sr2 + Sr32, Sr2 + Sr36, Sr36 + Sr44, Sr36 + Sr47, Sr32 + Sr44, Sr22 + Sr44, Sr31 + Sr36, Sr31 + Sr47, Sr31 + Sr44, Sr22 + Sr44 + Sr47, Sr22 + Sr31 + Sr32, Sr22 + Sr31 + Sr44, Sr22 + Sr36 + Sr44, Sr32 + Sr44 + Sr47, Sr31 + Sr36 + Sr47, Sr36 + Sr39 + Sr47, Sr2 + Sr22 + Sr36 + Sr44,Sr2 + Sr31 + Sr36 + Sr44, Sr22 + Sr32 + Sr40 + Sr44, Sr22 + Sr31 + Sr36 + Sr44, Sr2 + Sr22 + Sr32 + Sr44, Sr2 + Sr22 + Sr32 + Sr40 + Sr44. Specific features in transmission of some resistance genes are noted. In particular, no plants with the Sr24 gene were detected. The second feature is associated with the Sr2 gene (the gene was originally identified only in spring wheat 113/ 00i-4). The Sr2 gene was in a heterozygous state in more than 70% of winter plants in which

The presence of Sr32, Sr39, Sr40, Sr44 genes, which are poorly studied in relation to other Pgt races and rarely used in selection programs, with the resistance Sr2 gene of an adult plant showing "slow rusting" effect, gives particular value to the selected winter plants. However, the presence of the recessive Sr2 gene of resistance in the heterozygous state in most winter wheat plants will require additional efforts to transfer it to a homozygous state. In particular, we have planned experiments on the production of digaploid lines using androgenesis method. Individual plants with the identified genotype of resistance to stem rust differed greatly in height (75–145 cm), ear productivity (1.0–2.7 g), weight of 1000 grains (36–60 g) and morphological features. For further testing in infectious nurseries of stem and leaf rust, 373 individual winter wheat plants were selected: 199 plants with the identified Sr genes and 174 plants selected for a set of other economically valuable traits. From the populations of spring

Figure 3. Identification of the Sr2 gene using the molecular marker Xgwm533 in winter plants 1–36: M—molecular weight marker of 50 bp "Fermentas", Sr2—positive control Pavon76, K—negative control Saratovskaya 29 cultivar. The arrow indicates a diagnostic fragment with a molecular weight of 120 bp. The amplification products were separated in 2% agarose gel. "+"—presence of the diagnostic fragment; ""—absence of a diagnostic fragment; h—heterozygote.

plants and with five genes—4 plants.

192 Global Wheat Production

it was identified (Figure 3).

### 2.2.6.1. Spring wheat

Progeny testing of individual spring wheat plants was carried out against the infectious background for the North Caucasian and West Siberian populations of stem rust and leaf rust, and against the natural background of the disease course in the Moscow Oblast. It should be clarified that in the south of Russia (Krasnodar Krai), most of the known resistance genes are ineffective against the causative agent of stem rust. Genes Sr1, Sr5, Sr6, Sr9a, Sr9e, Sr13, Sr24, Sr27, Sr31, Sr32, Sr35, Sr36 remain effective [33]. One hundred and fifty-eight lines of spring wheat (or 81% of the number of studied lines) showed high resistance to infection (0R) by the North Caucasian population of stem rust, and 160 lines were resistant to leaf rust.

Testing of the same set of spring lines in Western Siberia (Omsk), which were sown with a special late spring sowing (late crops are more affected than those sown in the optimal time) led to the death of some lines, but from the 167 surviving lines, 111 lines (66.5%) with resistance to stem rust were selected. In the year of testing (2015), strong epidemic of stem rust was observed in the region. Under these conditions, only a small group of genes, according to the observations of the researchers, was effective (Sr2, Sr9e, Sr11, Sr12, Sr13, Sr19, Sr24, Sr25, Sr26, Sr27, Sr30, Sr31, Sr35 Sr37), but none of these genes provided full protection against the disease. The severity of lines with known resistance genes varied from 5 to 30% in comparison with 50–60% severity of cultivars without effective genes [34]. Selected in such harsh conditions, stable lines with group resistance to stem and leaf rust are valuable initial material for the selection of spring wheat in this region. Structural analysis performed in comparison with the standard cultivar Omskaya 37 allowed to select 20 lines with the least decrease in productivity in the unfavorable dry conditions of Western Siberia. In 2016, these lines were involved in crosses with the best adapted varieties cultivated in this region (Shamanin, personal communication).

In the Moscow Oblast, in 2015, no development of stem and leaf rust was observed even on the highly susceptible line Khakasskaya because of unfavorable weather conditions for the development of these pathogens (low air humidity, lack of dew, strong wind). However, in the Moscow suburbs, the spring lines were evaluated for resistance to powdery mildew. After that, the results of lines estimates at three geographic locations were combined, and genotypes that showed resistance simultaneously to leaf and stem rust in Krasnodar and Omsk and resistance to powdery mildew in the Moscow Oblast (71 genotypes) were selected. In 2016, under the conditions of epidemic development of stem rust in the Moscow Oblast, after negative selection for resistance to diseases, the timing of the ear formation, height and the presence of segregation by morphological features, 40 genotypes were left for further tests. After the statistical evaluation of the productivity elements (yield of grain from 0.3 m2 , productivity of the ear, weight of 1000 grains), 25 best genotypes with a set of economically valuable traits were selected (see Stage 7).
