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Potato virus Y (PVY) is considered as one of the most harmful virus infections of this crop. Thus, it is a topical problem to breed potato varieties resistant against a wide range of PVY strains and to create initial breeding material that will have a combination of resistance genes from different species. The aim of the study was: (1) to genotype a collection of 376 breeding lines (BL), developed from complex interspecific hybrids, using DNA markers of PVY resistance genes, (2) to identify accessions with markers of resistance genes from different species for subsequent use in marker assisted selection (MAS), (3) to evaluate the suitability of DNA markers of PVY resistance genes for genotyping BL developed through interspecific hybridization. It was ascertained that the markers most widely represented in the collection were RYSC3 of the Ry_adg gene (49.7%), Ry364 and RAPD38-530 of the Ry_chc gene (50.5% and 45.2%, respectively), and Yes3-3A of the Ry_sto gene (29.8%). The markers Ry186 of Ry_chc and GP122/EcoRV₇₈₀ of  Ry_f-sto  were found only in some accessions. The frequency of occurrence of BL that had markers of PVY resistance genes from two different species varied between 2.7% (Yes3-3a marker of Ry_sto and both two markers of Ry_chc) and 8.5-9.0% (RYSC3 marker of Ry_adg and both two markers of Ry_chc, or only Ry364 marker of this gene). In total, the collection was found to contain 134 BL (47.6%) with markers of resistance genes from two different species. A combination of four markers for three genes of different origin (Ry_adg, Ry_sto and Ry_chc) was found in 27 BL (7.2%). Extreme resistance to PVY of most BL (302 out of 357) was obviously determined by the presence in them of the currently used resistance genes detected by DNA markers applied in the study. Nevertheless, a significant part of accessions (55 of 61) that did not have any markers was resistant to PVY. At the same time, 13 BL (3.5%) with the markers were susceptible to the virus. Such a level of discrepancies is considered as acceptable for the initial MAS of breeding material. The obtained data on the presence of the markers of PVY resistance genes of different origin and their combination in BL ensures a more effective use of such BL in breeding in comparison with the BL resistant to the virus, though lacking corresponding markers. 

Abstract. Hybrid maize breeding requires constant renewal of the source material. In this regard, broadening of genetic variation in parental lines is one of the primary tasks in heterotic hybrid breeding programs. The use of reverse diploid inbred lines derived from a tetraploid population is considered as an innovative approach to achieve this goal.

Results. The investigated material comprised 106 reverse diploid (rediploid) inbred lines originating from diploid plants selected in segregating selfed progenies of triploid populations and consequently subjected to inbreeding, while triploid populations resulted from a cross between plants of a tetraploid population with a broad genetic basis and a diploid line. The use of a system of crosses with 37 sterile testers belonging to different FAO maize maturity groups allowed the evaluation of the rediploid lines’ combining ability and the response to M and C types of CMS. Field tests were conducted in 2019 in the steppe zone of Kabardino-Balkaria. Forty-six lines (43.3%) with the combining ability ranging from ultra-high to good, and 78 lines (73.6%) maintaining the CMS character were identified. Among them, 59 lines (55.7%) were maintainers for the M type CMS, 15 lines (14.1%)  for C type CMS, and 4 lines maintained sterility for both CMS types. Sixteen lines (15.1%) restored pollen fertility of the forms with M type CMS, 11 lines (10.4%) were restorers for the C-type and one line turned out to be a universal restorer for both CMS types. Ranking by the “sprout - flowering of ears” interstage period duration showed that most of the lines (66.0%) with the ability to maintain sterility or restore male fertility of M and C CMS types, as well as with the combining ability from ultrahigh to good (32.6%) fell into the group with the flowering period duration of 51-55 days. According to the results of the harvested grain moisture assessment, the hybrids ♀(РГС246с × OL213) × ♂92с5986_·2·3, ♀714М  ×  ♂1/67_-1 and ♀714М  ×  ♂92н136_-4, with the values of 13, 6%, 13.9%, 14.0%, respectively, were identified. The hybrids ♀714М × ♂1/67_{- 1} and ♀(OL563С × KL1392) × ♂92с0653 _{2 1 2} were characterized by the maximum value of the selection index, i.e. 5.03 and 5.13, respectively.

Conclusions. The results of the studies showed the breeding value of rediploid lines as an initial material for hybrid maize breeding. 

In order to involve valuable germplasm of the wild Mexican allotetraploid potato species Solanum stoloniferum Schltdl. (genomic composition ААВВ) into breeding, pentaploid interspecific hybrids (ААAAВ) with cultivated potato S. tuberosum L. (АААА) and their backcross progenies are usually used. Homologous synapsis in meiosis of such hybrids is expected only between chromosomes of the A subgenome, therefore a question arose about a possibility of introgressing genetic material of the subgenome B into the A genome of cultivated potato. In this connection, development of various schemes for the B subgenome introgression into the genome of cultivated potato is considered as a topical issue. The previous research has yielded four schemes of S. stoloniferum involvement into breeding, which imply backcrossing with cultivated potato of the following interspecific hybrids: (1) hexaploids (genomic composition ААААВВ, the conventional introgression scheme), (2) tetraploids (putatively, АААВ), (3) self-pollination progeny of a 4x hybrid and (4) pentaploid hybrids with a putative genome composition of АААВВ. The present paper presents the first results of the development of chromosome-specific DNA markers for the identification of S. stoloniferum chromosomes in interspecific hybrids. An S. stoloniferum accession PI 205522 with a high degree of resistance to late blight and PVY had been found to possess several DNA-markers of the R-genes conferring resistance to these pathogens and was used in hybridization as a promising parent. A set of 23 SSR- and CAPS markers with the known chromosome location in S. tuberosum was generated. These markers detect polymorphism between parent genotypes, i.e., the diploid clone IGC 10/1.21 of cultivated potatoes S. tuberosum, and accession PI 205522 of S. stoloniferum. All the markers specific for the wild species were found in triploid (ААВ) and pentaploid (АААВВ) hybrids of S. stoloniferum × S. tuberosum. This set of markers will be used for efficiency assessment of different schemes for S. stoloniferum genetic material introgression into the obtained BC2-BC3 generations after crossing the interspecific hybrids with cultivated potato.

The review presents data on the creation of complex microbial preparations and their application in agricultural practice. According to economists, the turnover in the field of organic agriculture is worth 85-90 billion US dollars a year. Developers of biological products pay great attention to the creation of complex biofertilizers, which contribute to a stable 20-25% increase in yield, with a significant reduction of plant damage by root rot. Among the considered positive effects of plant growth promoting rhizobacteria (PGPR) on plants are the ability to fix molecular nitrogen from the atmosphere, the synthesis of hormonal and fungitoxic substances, and the mobilization of sparingly soluble soil phosphates. The presented data show promise for the use of these microorganisms in the development of eco-friendly farming technologies in order to increase plant productivity and establish biocontrol over the development of plant diseases, reduce the chemical load on the soil, and increase its fertility.