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Background. Information is provided about the results obtained by screening the VIR collection of improved potato varieties for main commercial traits: earliness, high yield, high starch content, and resistance to late blight (Phytophthora infestans (Mont.) de Bary), viruses, and pests, such as cyst nematode (Globodera rostochiensis Woll. (Ro1)), and Colorado beetle (Leptinotarsa decemlineata Say).Materials and methods. Potato accessions representing domestic and foreign varieties from the VIR collection served as the material for this research. The screening was performed according to the techniques developed at the Potato Genetic Resources Department of VIR.Results and conclusion. Potato varieties with valuable commercial traits were identified as breeding sources promising for earliness: ‘Bashkirskiy’ (k-25338), ‘Charoit’ (k-25221), ‘Colleen’ (k-25224), ‘Lagun’ (k-25294), etc.; for high yield: ‘Ametist’ (k-25336), ‘Banba’ (k-25222), ‘Bastion’ (k-25198), ‘Nur-Alem’ (k-25253), ‘Senim’ (k-25306), etc.; for high starch content: ‘Charaўnik’ (k-25139), ‘Darnitsa’ (k-25179), ‘Lad’ (k-25180), ‘Maksimum’ (k-25136), etc.; for resistance to late blight: local variety (Georgia) (k-25298, k-25326), ‘Sunkar’ (k-25258), ‘Udovitskiy’ (k-25260), ‘Vektor’ (k-25200), ‘Zvezdochka’ (k-25209); for resistance to viruses: ‘Azart’ (k-25196), Gala (k-25270), ‘Nadezhda’ (k-25213), Utro (k-25219), ‘Volat’ (k-25263), etc. Varieties combining resistance to gold potato cyst nematode with other valuable commercial traits were selected. Varieties with relative resistance to Colorado potato beetle were isolated under favorable conditions for the pest’s development. As a result of the research, new source material was identified, with a potential to improve major commercial traits of potato: earliness, high yield, high starch content, resistance to late blight, viruses, and pests (cyst nematode and Colorado beetle).

Male sterility in potato is little studied since traditional breeding is based on the vegetative reproduction of highly heterozygous tetraploid varieties. The rapid development of hybrid diploid breeding contributes to growing interest in studying the male sterility of this important crop. In this work, a set of 6 cytoplasmic markers was employed to describe cytoplasmic genetic diversity of 185 potato cultivars bred in Russia and FSU countries. Three cytoplasm types were identified, T (40.0 %), D (50.8 %) and W/γ (8.7 %), which according to literature are associated with male sterility. With a single exception (0.5 %), cytoplasm types characteristic of male fertile forms (A, P) were not found in the subset of 185 cultivars. A comparison of these results with previously published data suggested expanding the subset to up to 277 cultivars, all developed in Russia or FSU countries; however, the resulting differentiation into three cytoplasm types (T, D and W/γ) was nearly the same. Fertility phenotyping helped identify both male-sterile and male-fertile genotypes within the three groups of varieties with T-, D- and W/γ-type cytoplasm. Fifteen genotypes differing in cytoplasm type and male sterility/fertility traits were selected for direct sequencing of 8 mtDNA loci. Fragments of the nad2, nad7, cox2, atp6 and CcmFc genes were identical in all 15 selected genotypes. The polymorphism, detected in the rps3, atp9 and CcmFc loci, was not associated with male sterility. Two SNPs in the nad1/atp6 and nad2 loci differentiated 7 genotypes with W/γ-type cytoplasm into five genotypes with tetrad sterility, and two with fertile pollen. The results of an NGS analysis confirmed the association of these SNPs with tetrad sterility in a larger set of 28 genotypes of different origin, all with W/γ-type cytoplasm. A heteroplasmy state was observed both in male-sterile and in male-fertile genotypes.

Background. The article presents the data obtained after the screening of potato cultivars for resistance to Phytophthora infestans (Mont.) de Bary. The selected genotypes combine late blight resistance with other valuable commercial traits, such as high yield, high starch content, resistance to virus dis­eases and potato nematode (Globodera rostochiensis Woll.).Materials and methods. Potato accessions representing do­mestic and foreign cultivars from the VIR collection served as the material for this research. The screening was performed according to the techniques developed at the Potato Genetic Resources Department of VIR.Results and conclusion. The following true-breeding cultivars were identified for their re­sistance to Phytophthora infestans: ‘Ania’ (k-24063), ‘Baszta’ (k-24067), ‘Bobr’ (k-21103), ‘Dunajec’ (k-24074), ‘Klepa’ (k-24080), ‘Koga’ (k-24174), ‘Meduza’ (k-24082) and ’Mors’ (k-24083) from Poland; ‘Caprice’ (k-25193), ‘Certo’ (k-19440) and ‘Valetta’ (k-21769) from Germany; ‘Avrora’ (k-12188), ‘Bastion’ (k-25198), ‘Bryansky nadezhny’ (k-12160), ‘Vdokh­noveniye’ (k-12192), ‘Vektor’ (k-25200), ‘Velikan’ (k-25201), ‘Zvezdochka’ (к-25209), ‘Kalinka’ (k-25148), ‘Lukyanovsky’ (k-11750), ‘Musinsky’ (k-25312), ‘Nakra’ (k-11916), ‘Nikulin­sky’ (k-12171), ‘Prizer’ (k-25217), ‘Rapsodiya’ (k-25258), ‘Rossiyanka’ (k-12057), ‘Rucheyek’ (k-12213) and ‘Udacha’ (k-11900) from Russia; ‘Aktsent’ (k-12237), ‘Vetraz’ (k-11989), ‘Vytok’ (k-11897), ‘Zhuravinka’ (k-12106), ‘Kupalinka’ (k-12155), ‘Sintez’ (k-11666), ‘Suzorye’ (k-11992) from Be­larus; ‘Vikhola’ (k-11270), ‘Zarevo’ (k-10773), ‘Svitanok ki­evsky’ (k-11665), ‘Olviya’ (k-25094), ‘Rakurs’ (k-25098) from Ukraine; ‘Aytmurat’ (k-25248), ‘Berkut’ (k-25250), ‘Zholbarys’ (k-25155), ‘Nur-Alem’ (k-25253), ‘Senim’ (k-25306), ‘Sey­anets Lapteva’ (k-25161), ‘Sunkar’ (k-25258), ‘Tamyz’ (k-25307) and ‘Udovitsky’ (k-25260) from Kazakhstan; etc. High percentage of plantlets resistant to late blight was ob­served among self-pollination progenies of cvs. ‘Avrora’ (k-12188), ‘Astra’ (k-10697), ‘Vikhola’ (k-11270), ‘Zhuravinka’ (k-12106), ‘Nayada’ (k-12157), ‘Rosinka’ (k-11993), ‘Skarb’ (k-11904), ‘Bobr‘ (k-21103) and ‘Clarissa’ (k-21770). There were cultivars combining late blight resistance with such traits as resistance to potato nematode (Globodera rosto­chiensis Woll.) and viruses, high productivity, and increased starch content: ‘Zhuravinka’, ‘Ania’, ‘Baszta’, ‘Bobr’, ‘Certo’ and ‘Mors’. The selected genotypes are recommended as promis­ing to be included in potato breeding programs.

Great damage to potato production is caused by cyst nematodes, which include two species: Globodera pallida (Stone) Behrens, the object of external quarantine, and Globodera rostochiensis (Wollenweber) Behrens, the object of internal quarantine in the Russian Federation. The breeding of varieties resistant to the G. rostochiensis has long been one of the priorities of Russian potato breeding, while a targeted search for sources of resistance to G. pallida in our country until recently was not actually carried out, since this pathogen was not detected in Russia, although it was traced in neighboring countries. The possibilities of selection of G. pallida-resistant genotypes using traditional phytopathological methods are extremely limited, so the information about the presence of markers of resistance genes to this pathogen in the domestic breeding gene pool is of particular importance.Here we present the results of molecular screening of 160 varieties bred in Russia and in adjacent countries from the collection of VIR for the presence of markers of Gpa2 gene, which provides resistance of potato varieties to G. pallida (Pa2/Pa3 pathotypes).It is shown that among 160 varieties of the analyzed subset 19 have a di­agnostic fragment of the allele-specific marker of the Gpa2 gene - Gpa2-2. These 19 varieties isolated in molecular screening simultaneously con­tained allele-specific markers of the Rxl gene controlling resistance to potato virus X (PVX).

Background. The article presents information on the results of screening potato cultivars for major commercial traits: earliness, high yield, high starch content, resistance to late blight (Phytophthora infestans (Mont.) de Bary), virus diseases and potato nematode (Globodera rostochiensis Woll. (Ro1)). Materials and methods. VIR’s collection of domestic and foreign potato cultivars served as the material for this research. The study was conducted in accordance with the guidelines developed at the Potato Genetic Resources Department of VIR. Results and conclusion. The analysis of pedigrees helped to select source material for the main trends of domestic potato breeding. Data of a number of cultivars identified by analyzing progenies from self-pollination are presented in the paper. Potential sources of major commercial traits were found: cvs. ‘Banba’ (k-25222), ‘Bastion’ (k-25198), ‘Belukha’ (k-25146), ‘Charoit’ (k-25221), ‘Colleen’ (k-25224), ‘Gala’ (k-25270), ‘Geyzer’ (k-25266), ‘Gornyak’ (k-25311), ‘Larets’ (k-25211), ‘Leoni’ (k-25244), ‘Manifest’ (k-25265), ‘Meteor’ (k-25212), ‘Nur-Alem’ (k-25253), ‘Prizer’ (k-25217), etc. were identified as high yield sources; cvs. ‘Aktyubinskiy-2’ (k-25300), ‘Alaya roza’ (k-25144), ‘Charaўnik’ (k-25139), ‘Darnitsa’ (k-25179), ‘Lad’ (k-25180), ‘Levada’ (k-25121), ‘Maksimum’ (k-25136), ‘Palitra’ (k-25123), ‘Tamyz’ (k-25307), ‘Universal’ (k-25137), ‘Vektor’ (k-25200), ‘Vytok’ (k-11897), ‘Zarevo’ (k-10773) and ‘Zholbarys’ (k-25155) as sources of high starch content; cvs. ‘Aral’ (k-25107), ‘Aymurat’ (k-25248), ‘Bastion’ (k-25198), ‘Berkut’ (k-25250), ‘Gastsinets’ (k-25264), ‘Musinskiy’ (k-25312), ‘Nur-Alem’ (k-25253), ‘Rapsodiya’ (k-25130), ‘Senim’ (k-25306), ‘Sunkar’ (k-25258), ‘Tamyz’ (k-25307), ‘Udovitskiy’ (k-25260), ‘Vektor’ (k-25200), ‘Velikan’ (k-25201), ‘Zholbarys’ (k-25155) and ‘Zvezdochka’ (k-25209) as sources of late blight resistance; cvs. ‘Adil’ (k-25112), ‘Azart’ (k-25196), ‘Bastion’ (k-25198), ‘Charoit’ (k-25221), ‘Favorit’ (k-25132), ‘Gastsinets’ (k-25264), ‘Geyzer’ (k-25266), ‘Krasavchik’ (k-25210), ‘Maksimum’ (k-25136), ‘Malyshok’ (k-25189), ‘Manifest’ (k-25265), ‘Nadezhda’ (k-25213), ‘Nur-Alem’ (k-25253), ‘Pamyati Lorkha’ (k-25214), ‘Rapsodiya’ (k-25130), ‘Senim’ (k-25306), ‘Sirenevyy tuman’ (k-25143), ‘Sultan’ (k-25131), ‘Shchedrik’ (k-25126), ‘Tekes’ (k-25173), ‘Velikan’ (k-25201), ‘Volat’ (k-25263), ‘Zhemchuzhina’ (k-25128), etc. as sources of field resistance to virus diseases. Cultivars combining resistance to potato cyst nematode (Globodera rostochiensis Woll. (Ro1)) with other valuable commercial traits were also identified.

The main objectives in potato breeding are increasing yield abilities and improving resistance to numerous pathogens and pests. Among them, the late blight caused by the Phytophthora infestans oomycete is one of the most destructive potato diseases both in Russia and worldwide. Wild relatives of cultivated potato are traditionally used in breeding as the source of valuable R genes conferring resistance to pathogens. Of particular interest are Mexican wild species because Mexico is the centre of origin and diversity of P. infestans and at the same time, it is the centre of potato species diversity. Mexican wild potato species S. bulbocastanum and S. stoloniferum are an important source of the R genes conferring broad-spec trum resistance against various isolates of P. infestans (Rpi-blb1, Rpi-blb2, Rpi-sto1). Recently these genes have been transferred into cultivated potato gene pool using the cisgene approach. At the same time there is a high probability of finding geno types with the Rpi-sto1 gene (functional homologues of Rpi-blb1) among conventionally bred varieties because for about 40 years S. stoloniferum has been used in breeding as a source of the Rysto and Ry-fsto genes of the extreme resistance to the most important viral pathogen PVY. In this study 188 potato varieties bred in Russia and in near-abroad countries were screened for the presence of six gene-specific markers of the RB/Rpi-blb1 = Rpi-sto1 and Rpi-blb2 genes conferring broad-spectrum resistance against P. infestans, and for the markers linked to the Rysto and Ry-fsto genes conferring extreme resistance to PVY. In addition, a marker for detecting male sterile mitochondrial DNA type gamma derived from S. stoloniferum was used. The genotypes selected through the molecular markers were divided into four groups: (A) 13 PVY resistant varieties carrying diagnostic markers of the Rysto, Ry-fsto genes and having sterile mt-type gamma; (B) four varieties possessing mt-type gamma and not having the markers of the R genes introgressed from S. stoloniferum; (C) eight genotypes carrying five gene-specific markers for the RB/Rpi-blb1/= Rpi-sto1; (D) the rest 166 (86.9 %) varieties not possessing any of the diagnostic markers associated with the S. stoloniferum genetic material. The sequences of the Rpi-sto1- and BLB1 F/R-amplicons were identical in all the genotypes of group ‘C’ and showed respective 99 % and 100 % similarity to the corresponding fragments of the Rpi-sto1 and Rpi-blb1 genes from the GenBank database. Among the genotypes of group ‘C’ various mt-types were detected, and some of them were male fertile.

The results of molecular screening of 103 Russian breeding varieties from the VIR potato collection are presented. These varieties were studied for the presence of diagnostic markers associated with the HI and Grol-4 genes conferring resistance to the golden potato cyst nematode - Globodera rostochiensis (Woll.) Behr. - pathotype Ro1. 25 varieties possessed the diagnostic markers of these genes. Among the nematode-resistant varieties, the frequency of genotypes with the diagnostic fragments of 57R and N195 markers of the Hl locus was 98%, and of marker Gro1-4-1 of the Grol-4 gene - 2%.

The article presents the results of studying VIR’s potato collection. Following such study, the best cultivars of potato are recommended as source material for breeding programs targeted at basic commercial traits, such as high yield, starch content, resistance to late blight (Phytophthora infestans (Mont.) de Bary) and Ro1 pathotype of golden potato cyst nematode (Globodera rostochiensis (Woll.) Behr.). Described here are the cultivars combining resistance to gold potato cyst nematode with other valuable commercial traits. The identified genotypes are recommended to be included in potato breeding programs.

Increasing the resistance of varieties to diseases and pests is a priority in potato breeding. Many potato varieties created in the Leningrad Scientific Research Institute of Agriculture “Belogorka” are multi-species hybrids possessing complex resistance to the most spread pathogens in combination with a high plasticity, which determined their zoning in many regions of the Russian Federation. Potato varieties and hybrids created in different periods of time in this institute and in the Ltd Breeding company “LiGa” were included in marker-assisted selection with 22 markers of 14 R genes conferring extreme resistance to viruses PVY and PVX, resistance to cyst nematodes Globodera pallida (patotypes Pa2, Pa3) and G. rostochiensis (pathotype Ro1) and resistance to late blight. The data of molecular screening were compared with the results of the State Test of Varieties for Disease Resistance, as well as with other published sources. Markers of sterile and fertile cytoplasm types were also used in the study. Based on the results of molecular screening, varieties and hybrids with different combinations of markers of R genes conferring resistance to the most harmful pathogens (Rysto, Ry-fsto, Rx1, Rx2, Gro1-4, H1, Gpa2, R1, R3a, Rpi-blb1, Rpi-sto1) were detected. Among them, genotypes with sterile D-, T-, W/gamma cytoplasmic types were selected. Analysis of their pollen fertility, crossability and pedigree data showed that breeders succeed in obtaining fertile forms with the D- and T-types of cytoplasm carrying genetic material of Mexican polyploid species Solanum stoloniferum and S. demissum. The information about the presence of markers of R genes and about cytoplasm types of hybrids and varieties will allow an effective implementation of further breeding programs for resistance to a complex of pathogens, including pyramiding of R genes. The data of molecular screening made it possible to specify the pedigrees of several varieties and hybrids that have been created over several decades.

The genetic diversity of potato varieties from the VIR collection was analyzed based on microsatellite analysis. These varieties have been bred in Russia and near-abroad countries since the 1931. Application of 14 highly polymorphic nuclear microsatellites (SSR) enabled the complete discrimination of all 113 varieties. Additionally, we have studied these varieties for the distribution of 8 DNA markers associated with three R-genes involved in the control of resistance to two quarantine objects: the potato wart Synchytrium endobioticum and golden potato cyst nematode Globodera rostochiensis, which occur locally in some regions of the Russian Federation. All the analyzed varieties with resistance to S. endobioticum pathotype 1 revealed the diagnostic marker Nl-251400 of the Sen1 gene and a few susceptible cultivars lost this diagnostic fragment. The tested markers of the H1 and Gro1-4 genes, which confer resistance to G. rostochiensis pathotype Ro1 revealed different predictiveness. In the molecular screening of potato varieties, it is better to use several markers of these genes. Results of molecular screening using six markers of the H1 and Gro1-4 genes allowed us to detect 6 haplotypes in the tested subset. Five haplotypes include varieties with different combinations of the markers tested, the majority (87.9 %) of these varieties were highly resistant or moderately resistant to G. rostochiensis. The most numerous haplotype H1/0 included 76 varieties, which did not possess any marker; 96.1 % of these varieties were susceptible to G. rostochiensis. Predictive associations between haplotype content, wart and nematode resistance, pedigree and ‘variety age’ are discussed.