Late blight resistance gene from Solanum ruiz-ceballosii is located on potato chromosome X and linked to violet flower colour

<p>Abstract</p> <p>Background</p> <p><it>Phytophthora infestans </it>(Mont.) de Bary, the causal organism of late blight, is economically the most important pathogen of potato and resistance against it has been one of the primary goals of potato breeding. Some potentially durable, broad-spectrum resistance genes against this disease have been described recently. However, to obtain durable resistance in potato cultivars more genes are needed to be identified to realize strategies such as gene pyramiding or use of genotype mixtures based on diverse genes.</p> <p>Results</p> <p>A major resistance gene, <it>Rpi-rzc1</it>, against <it>P. infestans </it>originating from <it>Solanum ruiz-ceballosii </it>was mapped to potato chromosome X using Diversity Array Technology (DArT) and sequence-specific PCR markers. The gene provided high level of resistance in both detached leaflet and tuber slice tests. It was linked, at a distance of 3.4 cM, to violet flower colour most likely controlled by the previously described <it>F </it>locus. The marker-trait association with the closest marker, violet flower colour, explained 87.1% and 85.7% of variance, respectively, for mean detached leaflet and tuber slice resistance. A genetic linkage map that consisted of 1,603 DArT markers and 48 reference sequence-specific PCR markers of known chromosomal localization with a total map length of 1204.8 cM was constructed.</p> <p>Conclusions</p> <p>The <it>Rpi-rzc1 </it>gene described here can be used for breeding potatoes resistant to <it>P. infestans </it>and the breeding process can be expedited using the molecular markers and the phenotypic marker, violet flower colour, identified in this study. Knowledge of the chromosomal localization of <it>Rpi-rzc1 </it>can be useful for design of gene pyramids. The genetic linkage map constructed in this study contained 1,149 newly mapped DArT markers and will be a valuable resource for future mapping projects using this technology in the <it>Solanum </it>genus.</p

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

Multivariate analysis of phenotypic diversity in the tetraploid × diploid hybrid progenies of potatoes

Osiemdziesiąt rodów ziemniaka uzyskanych z czterech interploidalnych krzyżowań 4x-2x zostało ocenione na 12 cech użytkowych, w tym morfologii bulw, w Instytucie Hodowli i Aklimatyzacji Roślin, Oddział Młochów w latach 2008–2009. Celem badań była ocena genotypowej różnorodności wśród rodów ziemniaka i uzyskanie wglądu w strukturę wielocechowej zmienności. Analiza składowych głównych (PCA) wyodrębniła pięć składowych głównych, które wyjaśniały 78,4% łącznej wariancji wśród rodów ziemniaka. Wykazana przez analizę PCA genotypowa różnorodność potomstwa 4x-2x daje szansę na wyselekcjonowanie wartościowych tetraploidalnych rodów zarówno na jadalny, jak i przetwórczy kierunek użytkowania. Spośród wyodrębnionych pięciu składowych głównych pierwsze trzy były najważniejsze. Pierwsza składowa (29,9% zmienności) była głównie skorelowana z regularnością kształtu, głębokością oczek i ciemnieniem enzymatycznym. Druga składowa, tłumacząca 16% łącznej zmienności była dodatnio skorelowana z plonem bulw, średnią masą bulwy i spłaszczeniem bulw. Trzecia składowa, wyjaśniająca 13,2% łącznej zmienności była pozytywnie skorelowana z zawartością skrobi i barwą chipsów.Eighty potato clones derived from interploid crosses 4x-2x were evaluated for 12 tuber morphological and agronomic traits at the Plant Breeding and Acclimatization Institute — National Research Institute, Research Center Młochów during 2008–2009. The objective of the research was to assess the genotypic diversity among potato clones and to gain insight into the structure of multivariable variation. The principal component analysis (PCA) distinguished five principle components which explained 78.4% of the total variance among potato clones. The demonstrated genotypic diversity of 4x-2x progenies gives the chance for selecting valuable tetraploid clones for both table and processing use. Out of five PCs, the first three were the most important. The first PC (29.9% of total variance) was mostly correlated with shape regularity, depth of eyes and enzymatic browning. The second PC, that explained 16.2% of the total variance, was positively correlated with tuber yield, mean tuber weight and tuber flatness. The third PC explaining 13.2% of the total variance was positively correlated with starch content and chip colour

The structure of multivariable phenotypic variation in potato progenies derived from tetraploid × diploid crosses

W IHAR, Oddział Młochów w latach 2008–2009, dla osiemdziesięciu rodów ziemniaka z czterech krzyżowań tetraploid × diploid przeprowadzono oceny pod kątem 12 cech użytkowych i jakościowych. Celem badań była ocena struktury wielocechowej zmienności. Eksploracyjna analiza czynnikowa (EFA) pozwoliła na wyodrębnienie 5 czynników odpowiedzialnych za 68% obserwowanej łącznej zmienności rodów. Wartości własne analizowanej macierzy korelacji dla tych czynników były większe od 1. Pierwszy czynnik (21,7% zmienności) był utworzony przez cechy odpowiedzialne za ogólny wygląd bulw (regularność kształtu, głębokość oczek, frekwencja bulw z wtórnym wzrostem). Drugi czynnik (15,5% zmienności), zwany czynnikiem plonotwórczym był skorelowany z plonem bulw, średnim ciężarem bulwy i stopniem spłaszczenia bulw. Trzeci czynnik (12,2% zmienności) określał przydatność do przetwórstwa i był skorelowany z dwoma wiodącymi cechami technologicznymi — zawartością skrobi i barwą chipsów. Czwarty czynnik (9,9% zmienności) został zinterpretowany jako wydłużenie bulw (korelacja z typem kształtu, frekwencją bulw spiczastych). Piąty czynnik (8,5% zmienności) był utworzony przez cechę wyglądu bulw. Wielowymiarowa struktura tej zmienności daje szansę na wyselekcjonowanie wartościowych tetraploidalnych rodów ziemniaka do użytkowania jadalnego, przetwórstwa spożywczego (chipsy, susze) oraz przetwórstwa na skrobię.In IHAR, Research Center Młochów during 2008–2009, eighty potato clones derived from the four tetraploid × diploid crosses were evaluated for 12 agronomic and tuber quality traits. The research objective was to examine the structure of multivariable variation. The first five axes of exploratory factor analysis (EFA) extracted 68% of the total variance among clones. Eigenvalues of the analyzed correlation matrix for these factors were above 1. The first factor (21.7% of total variance) was created by traits responsible for general appearance of tubers (shape regularity, depth of eyes, the frequency of tubers with the symptoms of secondary growth). The second factor (15.6% of total variance) was called a performance factor and was correlated with tuber yield, mean tuber weight and tuber flatness. The third factor (12.2% of total variance) called a suitability for processing was correlated with the two key processing traits: starch content and chip colour. The fourth factor (9.9% of total variance) was interpreted as tuber elongation since it was correlated with type of shape and the frequency of tubers with pointed ends. The fifth factor (8.5% of total variance) was correlated with the skin appearance. Multivariate structure of this variance gives a chance for selecting of valuable potato clones for: table use, processing into chips or dry-products and starch processing

The development of cold chipping potato parental lines for breeding cultivars suitable for processing

The objective of this research was to determine if variation for cold chipping exists in two breeding populations 4×-4× and 4×-2× potato hybrids. Twenty four potato genotypes of a population of 4×-4× hybrids (originated from crosses between parents with good chipping quality) were tested under field conditions at Młochów Research Center of the Plant Breeding and Acclimatization Institute over three years. Traits evaluated included: total tuber yield, marketable yield, starch content, chip colour after cold storage at 4°C, content of reducing sugars, tuber appearance. Out of 24 tested clones three have been selected with outstanding low accumulation of reducing sugars after cold storage (4°C), stable light chip colour and increased starch content. They were also described in trials as having moderate yielding ability, good tuber appearance and satisfied level of resistance to PVY, PLRV and Phytophthora infestans. Of four tested diploid parents in 4×-2× crosses, the DG 93-332 and the HT/HZ84-PH-151 were more suitable for creation of tetraploid generations combining low content of glucose with increased starch content, good yielding ability and satisfied tuber appearance

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