Late blight remains the most devastating disease in potato cultivation. The best protection against this disease could be achieved by durably resistant cultivars, but these do not exist at present. To advance resistance breeding, the search for resistant wild potato species and the characterization of their resistance is important. There have recently been a number of new developments in this area. For this reason, all wild potato species known to the authors in which resistance has been found to date are listed in this article with their respective genes and QTL. Lastly, an overview is given, how these new resistance sources can be used for future resistance breeding.

Late blight (LB) is the main potato disease worldwide and one of the most important ways to control it is the use of resistant varieties. Twenty-two potato clones from the B3 breeding population developed by the International Potato Center with high resistance to the disease and two susceptible controls were inoculated with four Peruvian complex isolates (POX67, PPA61, PLL69, and PPI112) of Phytophthora infestans, with complex virulence on potato. Whole plant inoculation assays were carried out under greenhouse and humid chamber conditions in Lima, Peru, and data obtained were correlated with data from field assays carried out in Oxapampa (Pasco), a CIP breeding site in the Peruvian rain forest. High significant correlations (α = 0.01) were found in the resistance to LB shown by potato clones, the values of the correlations under greenhouse conditions between the isolates POX67, PPA61, and PLL69 with the resistance in the field were r = 0.93, 0.92 and 0.80, respectively and under humid chamber conditions were r = 0.94, 0.93 and 0.94, respectively. Moderate correlations were found between resistance in the field and in the greenhouse (r = 0.69) and the field and in humid chamber conditions (r = 0.77) for inoculations with PPI112 isolate. The twenty-two clones tested in this study showed phenotypic stability for LB resistance according to non-parametric analysis.

Received: June 6th, 2022 ; Accepted: December 15th, 2022 ; Published: December 16th, 2022 ; Correspondence: rita.asakaviciute@lammc.lt | The results of research on the selection of potato varieties and breeding material fromInstitute for potato study NAAS and Institute of Agriculture of Carpathian Region NAAS arepresented in this paper.There were selected 12 potato varieties of Ukrainian breeding with high resistance level: ‘Aria’,‘Glazurna’, ‘Knyagynya’, ‘Zheran’, ‘Zhytnytsia’, ‘Podolyanka’, ‘Skarbnytsia’, ‘Slavyanka’,‘Chervona Ruta’, ‘Fantasy’, ‘Schedryk’ and ‘Chortytsia’ (1.2–2.4 points (R1) and 2 varieties(‘Dyvo’ and ‘Povin’ - 3.4 and 3.0 points (R2)) by the research results for potato assessment towart in 2020–2021 by the results of field and laboratory studies for determining Ukrainianbreeding potato varieties resistance to wart Synchytrium endobioticum (Schilb) Perc. There werechosen 6 varieties with relatively high resistance degree to late blight Phytophthora infenstans(Mont) de Bary (7.2–8.5 points): ‘Aria’, ‘Dyvo’, ‘Zhytnytsia’, ‘Knyagynia’, ‘Podolyanka’ and‘Slavyanka’ by the choice. The evaluation results allow to put them into the State Register ofplant varieties suitable for dissemination in Ukraine. These potato varieties recommend forimplementation in potato disease sources and usage as a parent form for crossing as sources ofpotato resistance to wart and late blight.

Potato production in Cameroon is constrained by biotic factors including bacterial wilt disease caused by Ralstonia solanacearum. No single method effectively controls this disease. Breeding for resistance is usually the best option for disease control in crops. Screening the potential parents for resistance under the target environmental conditions is the prerequisite for effective resistance breeding. This study aimed to determine the response to bacterial wilt of selected potato genotypes grown under different elevation levels and to identify suitable parents that can be used to develop resistant cultivars. The study was carried out in three elevations [high (>1800 m above sea level (m.a.s.l)), medium (1400–1800 m.a.s.l) and low (<1400 m.a.s.l)] in the Western Highlands zone of Cameroon. Seven potato genotypes were planted in a field of each elevation using a Complete Randomized Block Design with three replications. Inoculation occurred naturally. Disease parameters collected included days to onset wilting and bacterial wilt incidence (BWI). Yield components such as the total number of tubers per plant, the percentage of unmarketable tubers and the marketable yield were recorded. BWI as well as the percentage of unmarketable tubers decreased with elevation, meanwhile marketable yield increased with elevation. Disease development tended to be lower in all cultivars at higher elevations. The resistance of Dosa, Desiree, and Banso was high in all environments. based on these results, the combination of these two methods can lower the impact of bacterial wilt. Dosa can be grown at higher elevation fields for stable and higher yields.

Bacteria belonging to the Pectobacterium and Dickeya genera are globally distributed phytopathogens that are responsible for economically important soft rot and blackleg diseases of potatoes. Since 2014, there have been increased outbreaks of blackleg disease in the Eastern US, with many cases caused by an especially virulent, nearly clonal strain of Dickeya dianthicola. This disease is thought to be spread via commercial trade of seed tubers with latent infections of these bacteria. There is an urgent need to develop resistant potato varieties to help reduce the accidental spread and damage caused by these diseases. In this study, we conducted an iterative screen of US Potato Genebank (Sturgeon Bay, WI) collections to find wild potato relatives with resistance to tuber soft rot. We found several Solanum microdontum lines with high-level resistance that may be useful as source germplasm for breeding soft rot resistance into commercial potato varieties.

Late blight of potato and tomato, one of the most widely reported diseases of plants, is a significant curb in global agriculture which poses severe problems in terms of yield and economic losses, and environmental pollution due to pesticides use. The disease is caused by Phytophthora infestans -an oomycete - which first drew the considerable attention of plant pathologists during the mid-1840s when the pathogen incited historic starvation in Ireland – the great Irish potato famine - as a consequence of substantial potato losses due to late blight disease. Since that period, late blight has triggered several epidemics of potato and tomato of profound intensity in different regions. Over the course, synthetic fungicides have been proved effective management practice for late blight control; nonetheless, the evolution of new genotypes with increased virulence to hosts and resistance to fungicides has been greatly regarded as an agricultural problem. Breakthroughs in genome sequencing of P. infestans and identification of resistance genes in some plants have opened ways for the development of resistant genotypes. However, there still exist numerous challenges to deal with this noxious pathogen. This review aims to highlight the historical significance of late blight disease, its chemical control strategies and associated challenges, and resistance breeding programs by employing genetic approaches.

International audience | Potato wart disease is considered one of the most important quarantine pests for cultivated potato and is caused by the obligate biotrophic chytrid fungus Synchytrium endobioticum. This review integrates observations from early potato wart research and recent molecular, genetic, and genomic studies of the pathogen and its host potato. Taxonomy, epidemiology, pathology, and formation of new pathotypes are discussed, and a model for molecular S. endobioticum-potato interaction is proposed. Taxonomy Currently classified as kingdom: Fungi, phylum: Chytridiomycota, class: Chytridiomycetes, order: Chytridiales, family: Synchytriaceae, genus: Synchytrium, species: Synchytrium endobioticum, there is strong molecular support for Synchytriaceae to be transferred to the order Synchytriales. Hosts and disease symptoms Solanum tuberosum is the main host for S. endobioticum but other solanaceous species have been reported as alternative hosts. It is not known if these alternative hosts play a role in the survival of the pathogen in (borders of) infested fields. Disease symptoms on potato tubers are characterized by the warty cauliflower-like malformations that are the result of cell enlargement and cell multiplication induced by the pathogen. Meristematic tissue on tubers, stolons, eyes, sprouts, and inflorescences can be infected while the potato root system seems to be immune. Pathotypes For S. endobioticum over 40 pathotypes, which are defined as groups of isolates with a similar response to a set of differential potato varieties, are described. Pathotypes 1(D1), 2(G1), 6(O1), and 18(T1) are currently regarded to be most widespread. However, with the current differential set other pathogen diversity largely remains undetected. Pathogen-host interaction A single effector has been described for S. endobioticum (AvrSen1), which is recognized by the potato Sen1 resistance gene product. This is also the first effector that has been described in Chytridiomycota, showing that in this fungal division resistance also fits the gene-for-gene concept. Although significant progress was made in the last decade in mapping wart disease resistance loci, not all resistances present in potato breeding germplasm could be identified. The use of resistant varieties plays an essential role in disease managemen