Extreme resistance to Potato virus Y in potato carrying the Rysto gene is mediated by a TIR-NLR immune receptor

Potato virus Y (PVY) is a major potato (Solanum tuberosum L.) pathogen that causes severe annual crop losses worth billions of dollars worldwide. PVY is transmitted by aphids, and successful control of virus transmission requires the extensive use of environmentally damaging insecticides to reduce vector populations. Rysto , from the wild relative S. stoloniferum, confers extreme resistance (ER) to PVY and related viruses and is a valuable trait that is widely employed in potato resistance breeding programmes. Rysto was previously mapped to a region of potato chromosome XII, but the specific gene has not been identified to date. In this study, we isolated Rysto using resistance gene enrichment sequencing (RenSeq) and PacBio SMRT (Pacific Biosciences single-molecule real-time sequencing). Rysto was found to encode a nucleotide-binding leucine-rich repeat (NLR) protein with an N-terminal TIR domain and was sufficient for PVY perception and ER in transgenic potato plants. Rysto -dependent extreme resistance was temperature-independent and requires EDS1 and NRG1 proteins. Rysto may prove valuable for creating PVY-resistant cultivars of potato and other Solanaceae crops

Induction and application of dihaploids of potato (Solanum tuberosum L.)

The breeding work with common potato as a tetraploid crop is complicated. Reducing the tetraploid chromosome number to the diploid one, makes the research and breeding simpler, because tetrasomic inheritance is replaced with disomic. Dihaploids of S. tuberosum crossable to various diploid Solanum species give also possibility for direct gene transfer from the wild and primitive cultivated Solanum species to the S. tuberosum background. In this way the gene pool of common potato is improved and enriched, but there are also disadvantages connected with using of dihaploids and it is necessary to change the ploidy level back to the tetraploid one in order to produce a cultivar. In spite of that, dihaploids were utilized in several potato breeding programmes conducted in Europe and USA. Dihaploids contributed to many modern potato cultivars, facilitating genetic works

New sources of potato resistance to Phytophthora infestans at the diploid level

New sources of Phytophthora infestans (late blight) resistance are studied in two groups of diploids: complex Solanum hybrids and clones of pure wild  Solanum species. In more advanced studies complex hybrids of Solanum verrucosum, S. phureja and S. microdontum were involved, which were intercrossed in various combinations. In this group, clones with resistance both in leaflets and tubers have been selected. In addition, highly resistant to late blight hybrids are outstanding in chosen quality traits. Resistance to P. infestans identified in the advanced hybrids has been successfully transferred into 4x level with various extent. The second group of sources recently included in research covers about 110 clones of five wild Solanum species (S. berthaultii, S. kurtzianum, S. michoacanum, S. ruiz-ceballozii and S. pinnatisectum). In 1999-2003 preselection of leaflets and tuber resistant clones was performed. Selected clones have been simultaneously characterized for male fertility and big pollen grains (2n) formation

Quantitative Trait Loci for Resistance to Potato Dry Rot Caused by Fusarium sambucinum

Tuber dry rot is an important disease of potato caused by soil and seed-borne pathogens of the Fusarium genus leading to losses that may reach 60% of the yield. The goal of this work was to study the inheritance of the dry rot resistance in two diploid potato hybrid populations (11–36 and 12–3) with complex pedigrees, including several wild Solanum spp. We used an aggressive isolate of F. sambucinum for phenotyping both progenies, parents, and standard potato cultivars in laboratory tuber tests, in three subsequent years. The QTL for dry rot resistance were mapped by interval mapping on existing genetic maps of both mapping populations. The most important and reproducible QTL for this trait was mapped on chromosome I and additional year- and population-specific QTL were mapped on chromosomes II, VII, IX, XI, and XII, confirming polygenic control of this resistance. This is the first study mapping the loci affecting tuber dry rot resistance in potato genome that can contribute to better understanding of potato-F. sambucinum interaction and to more efficient breeding of resistant potato cultivars

Diploid potato hybrids — a source of resistance to potato wart disease (Synchytrium endobioticum (Schilb.) Perc.)

W latach 2006–2012 w IHAR — PIB w Radzikowie, w Pracowni Organizmów Kwarantan-nowych, oceniano diploidalne klony ziemniaka pod względem odporności na Synchytrium endobioticum (Schilb.) Perc. Klony te, wyselekcjonowane w IHAR — PIB w Młochowie, w Pracowni Genetyki, są mieszańcami międzygatunkowymi ziemniaka Solanum tuberosum powstałymi z udziałem dzikich i uprawnych gatunków Solanum. Klony testowano pod względem odporności na patotypy: 1(D1), 2(G1), 2(Ch1), 3(M1), 6(O1), 8(F1), 18(T1) i 39(P1) S. endobioticum, pochodzące z kolekcji Pracowni Organizmów Kwarantannowych. Testy oceny odporności na patotypy S. endobioticum wykonano zmodyfikowaną metodą Glynne-Lemmerzahla. Z 288 badanych klonów wyselekcjonowano 101 odpornych na patotyp 1(D1). Grupę 70 klonów testowano pod względem odporności na pięć patotypów 2(G1), 2(Ch1), 6(O1), 8(F1) i 18(T1) S. endobioticum, 44 z nich dodatkowo na patotyp 3(M1), a 22 klony dodatkowo na patotypy 3(M1) oraz 39(P1). W wyniku testów wyselekcjonowano siedem diploidalnych klonów ziemniaka jednocześnie odpornych na siedem wirulentnych patotypów S. endobioticum: 2(G1), 2(Ch1), 3(M1), 6(O1), 8(F1), 18(T1) i 39(P1). Są to wyjątkowo złożone rekombinanty pod względem odporności na patotypy S. endobioticum, jakich dotychczas nie opisano w innych pracach. Mieszańce te są materiałem do poszukiwania i lokalizacji na mapie genetycznej ziemniaka markerów sprzężonych z odpornością na poszczególne patotypy S. endobioticum. Odporne klony diploidalne charakteryzują się dobrym poziomem cech jakościowych i odpornościowych. Pięć z nich wytwarza męskie gamety o niezredukowanej liczbie chromosomów (gamety 2n), dzięki którym allele odporności na patotypy S. endobioticum można przekazać na poziom tetraploidalny w krzyżowaniach 4x × 2x.In 2006–2012 in IHAR — PIB Radzików, in Laboratory of Quarantine Organisms, diploid potato clones were tested for resistance to Synchytrium endobioticum (Schilb.) Perc. The diploid clones selected in IHAR — PIB Młochów, in Laboratory of Genetics, were interspecific hybrids of Solanum tuberosum possessing in their pedigree wild and primitively cultivated Solanum species. Clones were tested for resistance to following pathotypes of S. endobioticum: 1(D1), 2(G1), 2(Ch1), 3(M1), 6(O1), 8(F1), 18(T1), and 39(P1), from the collection of Laboratory of Quarantine Organisms. Modified method of Glynne-Lemmerzahl was used for evaluation of their resistance. From 288 tested clones 101 were found resistant to pathotype 1(D1). The group of 70 clones was tested for resistance to 5 pathotypes of S. endobioticum: 2(G1), 2(Ch1), 6(O1), 8(F1), and 18(T1); 44 clones from that group were evaluated additionally for the pathotype 3(M1) and 22 clones were assessed for 2 additional pathotypes 3(M1) and 39(P1). Selection resulted with 7 diploid clones simultaneously resistant to 7 virulent pathotypes of S. endobioticum: 2(G1), 2(Ch1), 3(M1), 6(O1), 8(F1), 18(T1), and 39(P1). They are complex recombinants combining resistance to wart disease agent pathotypes that have not been described in other studies, so far. Selected resistant hybrids are excellent material for identification and localization on potato genetic map of genetic markers linked to the resistance to particular pathotypes of S. endobioticum. These diploid clones exhibit a good level of quality and resistance traits. Five of them produce male 2n gametes which can be used in 4x × 2x crosses for transfer of alleles of resistance to wart disease agent pathotypes to tetraploid level