Search

International audience; Apple scab, caused by Venturia inaequalis, is a major disease worldwide. To control this disease, up to 20-25 fungicide applications may be needed depending on the year and the production system. Cultivation of scab-resistant apple cultivars would reduce the chemical footprint of apple production. Breeding for durable scab resistance is an objective of most apple breeding programmes. One way to achieve durable resistance is to pyramid multiple apple scab resistance genes in a cultivar. Currently, more than 18 different apple scab resistance genes have been reported. Molecular markers are available for most of these and can be used to select seedlings carrying multiple resistance genes. Apple scab isolates are virulent to specific apple scab resistance genes. Choice of optimal resistance genes for use in a breeding program, should therefore take regional presence of these apple scab isolates into consideration. In order to learn more about the geographical distribution of apple scab isolates, the VINQUEST project (www.vinquest.ch) was initiated in 2009. Ten years after the launch of this initiative, 24 partners from 14 countries are regularly contributing data. Results obtained from the data collected during the first 10 years provide the first insights into which apple scab resistance genes may hold most promise for breeding cultivars with durable resistance.

International audience; Apple scab, caused by Venturia inaequalis, is a major fungal disease worldwide. Cultivation of scab-resistant cultivars would reduce the chemical footprint of apple production. However, new apple cultivars carrying durable resistances should be developed to prevent or at least slow the breakdown of resistance against races of V. inaequalis. One way to achieve durable resistance is to pyramid multiple scab resistance genes in a cultivar. The choice of the resistance genes to be combined in the pyramids should take into account the frequency of resistance breakdown and the geographical distribution of apple scab isolates able to cause such breakdowns. In order to acquire this information and to make it available to apple breeders, the VINQUEST project (www.vinquest.ch) was initiated in 2009. Ten years after launching this project, 24 partners from 14 countries regularly contribute data. From 2009 to 2018 nearly 9000 data points have been collected. This information has been used to identify the most promising apple scab resistance genes for developing cultivars with durable resistance, which to date are: Rvi5, Rvi11, Rvi12, Rvi14 and Rvi15. As expected, Rvi1, together with Rvi3 and Rvi8, were often overcome, hence have little value for scab resistance breeding. Rvi10 may also belong to this group. On the other hand Rvi2, Rvi4, Rvi6, Rvi7, Rvi9, and Rvi13 are still useful for the breeding, but their use is recommended only in extended pyramids of (≥3) resistance genes.

In this paper, the microsatellite (SSR) loci analysis was used to study apple genotypes with different levels of ploidy. A total of 47 samples were studied (9 diploids, 21 triploids, and 17 tetraploids) for seven microsatellite loci (GD147, Hi02C07, CH02c11, CH04c07, CH03d07, CH02c09, and GD12). It was possible to refine the pedigrees for some forms. It was established that the tetraploidss 20-9-30 and 20-9-27, selected in a hybrid family from the crossing of Wealthy 4x and Antonovka Obyknovennaya, were probably obtained from the self-pollination of the maternal form, since in the most loci they did not inherit alleles from the paternal form. As a result of the alleles distribution analysis, the spontaneous triploid cultivars Nizkorosloe and Sinap Orlovsky were revealed to be formed from the merge of an unreduced ovum and haploid pollen, since in the heterozygous loci both alleles are inherited from the maternal form and only one from the paternal form. According to the obtained data, studied tetraploids may be divided into two groups, which also reflect the features of tetraploids origin. The first group includes tetraploids inherited alleles from one initial diploid form (including spontaneous and induced tetraploids, as well as forms from self-pollination of the tetraploid maternal form). These teraploids, like diploids, amplify 1–2 alleles per locus (on average, for all 7 loci, one genotype amplifies 13 alleles). The second group includes tetraploids carrying alleles from several initial diploid forms. Tetraploids of this group are highly heterozygous and amplify 3–4 alleles at most loci (the maximum number of alleles at all loci, 24 alleles, was identified in the form 30-47-88). Tetraploids of the second group have a greater potential for the genetic diversity of its offspring. Analysis of polymorphism of microsatellite loci can be used (1) as an alternative or additional method for identifying the triploid hybrids from heteroploid crosses of orthoploid forms, which is based on the analysis of the loci most polymorphic in parental forms, and (2) for the analysis of true hybridity (verification of pedigrees), including tetraploid forms. Moreover, we identified the most polymorphic loci suitable for the above purposes. The aspects of qualitative and quantitative interpretation of the fragment analysis of microsatellite loci results are considered. The possibilities and limitations of the SSR analysis for detection of apple ploidy level are discussed.

Based on the analysis of SSR loci, the genetic similarity of 32 pear cultivars (Pyrus) from the VNIISPK collection was studied. A cluster analysis of the genetic similarity of genotypes was carried out using 19 microsatellite markers. Based on the data obtained, a dendrogram was constructed using the UPGMA method using the Jacquard coefficient and bootstrap (BP) analysis. The coefficients of pairwise genetic similarity between the varieties ranged from 0.4 (between Podgoryanka and the Bere Russkaya, Mramornaya group) to 0.85 (between Osennyaya Zheltaya and Pervomayskaya). This group had a high BP level– 100% and a close genetic distance – 0.85), and the reliability level (BP,%) was indicated on the dendrogram at a value of more than 50%. According to the clustering results, the pear samples did not form large groups with high BP, which indicated the sufficient genetic diversity of the studied cultivars. There are only three small groups with high BP. Two of them combined two cultivars with a common origin. Thus, Bere Russkaya and Mramornaya, which are descendants from the crossing of Bere Zimnya Michurina × Lesnaya Krasavitsa, joined into one cluster with BP 82. Another group with BP 92 united Viliya and Zaveya, which also have the same origin ([Belorusskaya Pozdnya × (Bere Seraya × Dulya Ostzeyskaya)] × Maslyanaya Ro). The third group combined the cultivars Osennyaya Zheltaya (origin is not known) and Pervomayskaya (Doch Zari × Pozdnya MOSVIR) with BP 100 and the cultivar Prosto Maria ([Belorusskaya Pozdnya × (Bere Seraya × Dulya Ostzeyskaya)] × Maslyanaya Ro) with BP 100 adjoins them at a extended genetic distance. There is no obvious similarity in origin in this cluster. The SSR-analysis method opens up broad prospects in studying the genetic similarity of cultivars.

This paper gives the development history of the best apple cultivar of the temperate zone of Russia— the Sinap Orlovsky apple cultivar with fruit of a long storage life, which has hitherto been considered to be a diploid one. The assumption of its triploidy has come into existence due to DNA-markers. Cytoembryological studies showed in 2016 that the cultivar was a triploid. It is characterized by vigorousness and regular fruit bearing. The long-term experimental data show that the cultivar is of little promise as an initial form for the development of a large hybrid fund owing to its low fruit output, hybrid seeds, and one-year seedlings relative to pollinated flowers in case of its being used as a maternal and paternal parent.

This study was the first time in Russia to carry out a large-scale (127 samples) assessment of the diverse gene pool of black currant and red currant, the study of intervarietal polymorphism between varieties of the Ribes L. genus from the VNIISPK collection. A cluster analysis of the genetic similarity of black currant varieties (53 varieties), red currant (73 varieties) and one gooseberry variety was performed using 14 SSR markers. Based on the data obtained, a dendrogram was built, in which a number of clusters with high bootstrap support (BS, %) were distinguished. At BS>50%, the coefficients of pairwise genetic similarity between varieties varied from 0.4 to 0.91. The studied representatives of the Ribes genus merged into two main clusters of red currant and black currant. The blackcurrant cluster was joined by gooseberries. The SSR analysis method allows to reveal broad perspectives in the field of identifying varieties affiliation to species.

Pedigree Based Analysis (PBA) is an innovative and powerful approach for the discovery and characterisation of marker-trait associations for use in marker assisted breeding. The power of PBA comes from the simultaneous analysis of multiple segregating full sib families, the use of breeding germplasm, and the use of known genetic relationships. The use of multiple families allows representation of wide genetic diversity thus increasing probability that desired genes/alleles are presented and segregating. This also allows examination of QTL performance across different genetic backgrounds, thus providing knowledge on the general applicability of results. Finally, the use of multiple families increases the population size and thereby the statistical power. The use of breeding germplasm of ongoing breeding activities makes results directly applicable and relevant to the breeder and also reduces experimental costs since plant materials and part of the phenotypic measurements are already available. Finally, PBA provides a framework for extending the population and phenotypic data in time, thereby further strengthening statistical power. The statistical approaches and software have been validated through an integrated study on 27 families from five breeding programs from four countries [1] from which some results are presented in figures 1 &2. Current PBA software includes FlexQTLTM for QTL discovery and characterization [1], Pedimap for the graphical presentation [2], Visual-FQ, which provides structured guidance through the analyses and FQ-haplotyper which assigns alleles to haploblocks (sets of tightly linked SNP markers).

WOS: 000335066300001, PubMed ID: 24581289, Background: Breeders in the allo-octoploid strawberry currently make little use of molecular marker tools. As a first step of a QTL discovery project on fruit quality traits and resistance to soil-borne pathogens such as Phytophthora cactorum and Verticillium we built a genome-wide SSR linkage map for the cross Holiday x Korona. We used the previously published MADCE method to obtain full haplotype information for both of the parental cultivars, facilitating in-depth studies on their genomic organisation. Results: The linkage map incorporates 508 segregating loci and represents each of the 28 chromosome pairs of octoploid strawberry, spanning an estimated length of 2050 cM. The sub-genomes are denoted according to their sequence divergence from F. vesca as revealed by marker performance. The map revealed high overall synteny between the sub-genomes, but also revealed two large inversions on LG2C and LG2D, of which the latter was confirmed using a separate mapping population. We discovered interesting breeding features within the parental cultivars by in-depth analysis of our haplotype data. The linkage map-derived homozygosity level of Holiday was similar to the pedigree-derived inbreeding level (33% and 29%, respectively). For Korona we found that the observed homozygosity level was over three times higher than expected from the pedigree (13% versus 3.6%). This could indicate selection pressure on genes that have favourable effects in homozygous states. The level of kinship between Holiday and Korona derived from our linkage map was 2.5 times higher than the pedigree-derived value. This large difference could be evidence of selection pressure enacted by strawberry breeders towards specific haplotypes. Conclusion: The obtained SSR linkage map provides a good base for QTL discovery. It also provides the first biologically relevant basis for the discernment and notation of sub-genomes. For the first time, we revealed genomic rearrangements that were verified in a separate mapping population. We believe that haplotype information will become increasingly important in identifying marker-trait relationships and regions that are under selection pressure within breeding material. Our attempt at providing a biological basis for the discernment of sub-genomes warrants follow-up studies to streamline the naming of the sub-genomes among different octoploid strawberry maps., Technological Top Institute Green Genetics [1C004RP]; Socrates-Erasmus Student Exchange Programme, The Socrates-Erasmus Student Exchange Programme is acknowledged for the fellowship awarded to Hulya Yilmaz Temel. Tom Davis, University of New Hampshire, is acknowledged for sharing sequence information for the design of the primers TDFM1, -2, and -6, and Paul Arens, Wageningen UR Plant Breeding is acknowledged for the design of these specific primers. Funding for this research was provided through the Technological Top Institute Green Genetics, project number 1C004RP.

Progenies of ‘Schmidt's Antonovka’ (SA) have been widely used in Western breeding programs as a source of scab resistance. The identity of SA has remained obscure, especially due to the existence of a series of ‘Antonovka’ cultivars with different origins. In this paper we show Schmidt's Antonovka to be identical to ¿¿¿¿´¿¿¿¿¿ ¿¿¿¿¿¿¿¿¿¿¿¿ or ‘Common Antonovka’ (CA), an old Russian cultivar of unknown origin, by comparing simple sequence repeat (SSR) and SNP genotyping data from several first-generation descendants of SA from two European collections and a CA accession from the germplasm collection held at VNIISPK (The All-Russian Research Institute of Horticultural Breeding, Orel, Russia). The use of CA in Russian breeding programs is also briefly reviewed.