Stability of agronomic traits in interspecific hybrid potato clones in the Central Region of European Russia

Background. Yield stability is a necessary trait for sustainable potato production under climate change. Potato breeding is based on crosses between parental lines selected for a set of important traits: productivity, structural yield components, and resistance to abiotic and biotic stresses. Data on plant responses to environmental conditions allows breeders to conduct informed selection of plant forms for crossing. The objective of this work was to characterize interspecific potato hybrids in terms of their productivity, yield plasticity and stability in the Central Region of European Russia.Materials and methods. For seven years (2014–2020), 19 hybrids and cv. ‘Favorit’ (reference) were assessed for productivity, number of tubers per plant, mean tuber weight, marketability, and resistance to late blight. Growing conditions were characterized using the hydrothermal coefficient. Environmental sustainability was determined by calculating the parameters of plasticity (bI) and stability (σ2) according to N. P. Sklyarova and V. A. Zharova.Results. Positive and negative anomalies in heat or moisture supply were observed during the test years. The maximum productivity was obtained in 2016, with heavy rainfall and higher temperatures; the minimum, in the hot and dry 2018. For productivity, the effect sizes of the factors “variety” and “year” were 29% and 38%, respectively. Hybrids with yield levels close to cv. ‘Favorit’ were identified: 117-2, 122-29, 99-6-5, 99-1-3, 99-6-6, and 34-5-2003. ‘Favorit’ is an intensive-type cultivar, with low yield stability. Hybrid 135-2-2006, also of the intensive type, had a stable yield, but developed medium-sized tubers and was less productive than other accessions. Hybrid 117-2 is of the extensive type, with medium stability, while hybrids 8-3-2004 and 135-5-2005 demonstrated high environmental plasticity and yield stability.

Quality Evaluation, Phytochemical Characteristics and Estimation of Beta-Carotene Hydroxylase 2 (Chy2) Alleles of Interspecific Potato Hybrids

Potatoes contain antioxidants such as flavonoids, carotenoids and ascorbic acid. High level consumption worldwide makes potato a valuable source of phytonutrients. Developing new potato varieties with high nutritional value in combination with resistance to pathogens is an important task. In this study, 25 interspecific potato hybrids with resistance to Synchytrium endobioticum, common scab, silver scab, rhizoctonia, nematodes and PVY were evaluated for total phenolics, total flavonoids, total carotenoids, ascorbic acid contents and antioxidant activity. The identification of the dominant allele related with yellow flesh color at the Chy locus was also performed by the specific CAPS marker. Total protein content was detected and ranged from 8.19 ± 0.59 to 30.17 ± 4.56 mg/g dry weight (DW). Total starch and total carbohydrate contents were in the range of 9.0–21.0% and 73.21 ± 20.94–676.36 ± 195.28, respectively. Total phenolic content of hybrids varied from 8.45 to 82.75 mg/100 g, and total flavonoids content—from 0.64 to 9.67 mg/100 g DW. It is possible to distinguish samples with high protein and carbohydrate contents, high level of substances with antioxidant activity and characterized by resistance to pathogens. Quality evaluation has shown that some of the samples have a high potential for processing and chip production in combination with high eating qualities. These samples can be used in breeding programs to develope varieties resistant to pathogens and with high nutritional value.

Stacking Resistance Genes in Multiparental Interspecific Potato Hybrids to Anticipate Late Blight Outbreaks

Stacking (pyramiding) several resistance genes of diverse race specificity in one and the same plant by hybridization provides for high and durable resistance to major diseases, such as potato late blight (LB), especially when breeders combine highly efficient genes for broad-spectrum resistance that are novel to the intruding pathogens. Our collection of potato hybrids manifesting long-lasting LB resistance comprises, as a whole, the germplasm of 26 or 22 Solanum species (as treated by Bukasov and Hawkes, respectively), with up to 8–9 species listed in the pedigree of an individual hybrid. This collection was screened with the markers of ten genes for race-specific resistance to Phytophthora infestans (Rpi genes) initially identified in S. demissum (R1, R2, R3a, R3b, and R8), S. bulbocastanum/S. stoloniferum (Rpi-blb1/ Rpi-sto1, Rpi-blb2, Rpi-blb3) and S. venturii (Rpi-vnt1). The hybrids comprised the markers for up to four-six Rpi genes per plant, and the number of markers was significantly related to LB resistance. Nevertheless, a considerable portion of resistance apparently depended on presently insufficiently characterized resistance genes. Bred from these multiparental hybrids, the advanced lines with the stacks of broad-specificity Rpi genes will help anticipate LB outbreaks caused by rapid pathogen evolution and the arrival of new pathogen strains.

Identification of Interspecific Potato Hybrids with Combined Resistance to Late Blight (Phytophthora Infestans) and Nematode (Globodera Rostochiensis)

Late blight (agent Phytophthora infestans) and potato cyst nematode (PCN) caused by Globodera rostochiensis are economically important pathogens, which may significantly reduce potato yields. In this study interspecific potato hybrids were used as a source of resistance for combined resistance to economically important potato pathogens: late blight and cyst nematode. The aim of our study was to identify hybrid progenies with combined resistance to both pathogens and to verify the applicability of several molecular markers associated with resistance to G. rostochiensis pathotype Ro1 to identify resistant plants. Ninety-two clones of eleven original interspecific potato hybrids obtained in crosses with the cultivated S. tuberosum group tuberosum, S. tuberosum group Andigena, S. tuberosum group Phureja and wild S. guerreroense, S. microdontum, S. kurtzianum, S. neoantipoviczii and S. tarijense potato species were screened in bioassays and by molecular markers. PCN resistant or moderately resistant clones were found among the progenies of nine hybrids. Results were highly correlated with resistance status detected by molecular markers linked to the H1 (marker 57R) and Gro1-4 (marker Gro1) genes. Marker CP113 (linked to the H1 gene) was not polymorphic and failed to detect resistance status. Combination of foliar late blight resistance and resistance to PCN was identified in hybrids obtained in crosses with plants of species S. microdontum, S. tarijense and S. phureja and in the hybrid between S. guerreroense and Black’s P. infestans race differential carrying gene R-5.

South American species Solanum alandiae Card. and S. okadae Hawkes et Hjerting as potential sources of genes for potato late blight resistance

For several decades, wild species of Solanum L. section Petota Dumort. have been involved in potato cultivar breeding for robust resistance to pests and diseases. Potato late blight (LB) is caused by oomycete Phytophthora infestans (Mont.) de Bary, and the genes for race-specific resistance to P. infestans (Rpi genes) have been introgressed into cultivated potatoes by remote crosses and trans- or cisgenesis, first from S. demissum Buk. and, more recently, from other wild species, such as S. bulbocastanum Dun., S. stoloniferum Schlechtd. et Bché, and S. venturii Hawkes et Hjerting (according to the nomenclature by Hawkes, 1990). Most wild species already involved in breeding for LB resistance came from North and Central Americas: series Bulbocastana (Rydb.) Hawkes, Demissa Buk. and Longipedicellata Buk., and some Rpi genes of these species have been already characterized in much detail. Rpi genes of South American species, including the series Tuberosa (Rydb.) Hawkes, have not been sufficiently investigated. Among the latter, this study focuses on the Rpi genes of S. alandiae Card. and S. okadae Hawkes et Hjerting. Four accessions of S. alandiae, one accession of S. okadae and 11 clones of interspecific potato hybrids comprising S. alandiae germplasm from the VIR collection were PCR-screened using specific SCAR (Sequence Characterized Amplified Region) markers for eight Rpi genes. SCAR amplicons of five Rpi genes registered in this study were validated by comparing their sequences with those of prototype genes deposited in the NCBI Genbank. Among the structural homologues of Rpi genes found in S. alandiae and S. okadae, of special interest are homologues of CC-NB-LRR resistance genes with broad specificity towards P. infestans races, in particular R2=Rpi-blb3, R8, R9a, Rpi-vnt1 and Rpi-blb2 (94–99, 94–99, 86–89, 92–98 and 91% identity with the prototype genes, respectively). Our data may help to better understand the process of Rpi gene divergence along with the evolution of tuberbearing Solanum species, particularly in the series Tuberosa.