Potato Population Research Articles

Integrative multi-omics analysis reveals genetic and heterotic contributions to male fertility and yield in potato.

The genetic analysis of potato is hampered by the complexity of tetrasomic inheritance. An ongoing effort aims to transform the clonally propagated tetraploid potato into a seed-propagated diploid crop, which would make genetic analyses much easier owing to disomic inheritance. Here, we construct and report the large-scale genetic and heterotic characteristics of a diploid F2 potato population derived from the cross of two highly homozygous inbred lines. We investigate 20,382 traits generated from multi-omics dataset and identify 25,770 quantitative trait loci (QTLs). Coupled with gene expression data, we construct a systems-genetics network for gene discovery in potatoes. Importantly, we explore the genetic basis of heterosis in this population, especially for yield and male fertility heterosis. We find that positive heterotic effects of yield-related QTLs and negative heterotic effects of metabolite QTLs (mQTLs) contribute to yield heterosis. Additionally, we identify a PME gene with a dominance heterotic effect that plays an important role in male fertility heterosis. This study provides genetic resources for the potato community and will facilitate the application of heterosis in diploid potato breeding.

Analysis of hybrid potato populations in the conditions of the Magadan region

The priority direction in potato breeding in the Magadan region, given the short growing season and heat shortage, is the creation of predominantly early-ripening potato varieties. The article presents the results of the evaluation of potato breeding samples in terms of productivity and ripeness. Over two years, about three thousand samples of 67 hybrid combinations have been studied. The research was carried out in 2022–2023 on the experimental field of the Magadan Scientific Research Institute of Agriculture on floodplain, sod-alluvial, pebble-sandy loam soils. More than two thousand samples represented by 25 hybrid combinations were studied in the nursery of seedlings. Hybrid combinations characterized by a high frequency of selection of promising forms are identified, such as Arctica × Elbeida, Udacha × Bellarosa, Krone × Bellarosa, Charoite × Bellarosa, Krone × Labadia, Arctica × Gala. In these hybrid combinations, from 7.6 to 17.9% of the samples from the total number of the seedlings planted in the field were selected as clones. The samples with high productivity indicators were selected in the nursery of hybrids of the 1st year. The maximum weight of tubers of one plant was noted in the populations of Columba × Krepysh – 2010, Udacha × Bellarosa – 1820, Arctica × Elbeida – 1825, Charoite × Bellarosa – 1800. In the nursery of hybrids of the 2nd year, hybrids with productivity exceeding 1000 g/bush, such as Columba × Krepysh (2700 g/bush), Udacha × Bellarosa (1950 g/bush), Arctica × Krepysh (1670 g/bush), were identified in terms of yield and economically valuable characteristics. The frequency of selection of productive clones here exceeded 50%. These hybrid combinations are recommended for breeding research in the conditions of the Magadan region.

Genomic prediction for potato (Solanum tuberosum) quality traits improved through image analysis.

Potato (Solanum tuberosum L.) is the most widely grown vegetable in the world. Consumers and processors evaluate potatoes based on quality traits such as shape and skin color, making these traits important targets for breeders. Achieving and evaluating genetic gain is facilitated by precise and accurate trait measures. Historically, quality traits have been measured using visual rating scales, which are subject to human error and necessarily lump individuals with distinct characteristics into categories. Image analysis offers a method of generating quantitative measures of quality traits. In this study, we use TubAR, an image-analysis R package, to generate quantitative measures of shape and skin color traits for use in genomic prediction. We developed and compared different genomic models based on additive and additive plus non-additive relationship matrices for two aspects of skin color, redness, and lightness, and two aspects of shape, roundness, and length-to-width ratio for fresh market red and yellow potatoes grown in Minnesota between 2020 and 2022. Similarly, we used the much larger chipping potato population grown during the same time to develop a multi-trait selection index including roundness, specific gravity, and yield. Traits ranged in heritability with shape traits falling between 0.23 and 0.85, and color traits falling between 0.34 and 0.91. Genetic effects were primarily additive with color traits showing the strongest effect (0.47), while shape traits varied based on market class. Modeling non-additive effects did not significantly improve prediction models for quality traits. The combination of image analysis and genomic prediction presents a promising avenue for improving potato quality traits.

Mapping of a novel locus Ra conferring extreme resistance against potato virus A in cultivated potato (Solanum tuberosum L.).

The Ra extreme resistance against potato virus A was mapped to the upper of chromosome 4 in tetraploid potato. Potato virus A (PVA) is one of the major viruses affecting potato worldwide and can cause serious disease symptoms and yield losses. Previously, we determined that potato cultivar Barbara harbors Rysto (genotype: Ryryryry) and Ra (genotype: Rararara) that each independently confer extreme resistance to PVA. In this study, employing a combination of next-generation sequencing and bulked-segregant analysis, we further located this novel Ra on chromosome 4 using a tetraploid BC1 potato population derived from a Ry-free progeny (Rararararyryryry) of Barbara (RarararaRyryryry) × F58050 (rararararyryryry). Using 29 insertion-deletion (InDel) markers spanning chromosome 4, Ra was delimited by the InDel markers M8-83 and M10-8 within a genetic interval of 1.46cM, corresponding to a 1.86-Mb genomic region in the potato DM reference genome. The InDel marker M10-8, which is closely linked with the resistance against PVA in the Ry-free segregating populations, was then used to screen 43 selected Rysto-free tetraploid potato breeding clones. The phenotype to PVA was significantly correlated with the present/absent of the marker, albeit with a 9.3% false positive rate and a 14.0% false negative rate. These findings are of importance in furthering the cloning of Ra and employing the marker-assisted selection for PVA resistance.

Promiscuous potato: elucidating genetic identity and the complex genetic relationships of a cultivated potato germplasm collection.

A total of 3,860 accessions from the global in trust clonal potato germplasm collection w3ere genotyped with the Illumina Infinium SolCAP V2 12K potato SNP array to evaluate genetic diversity and population structure within the potato germplasm collection. Diploid, triploid, tetraploid, and pentaploid accessions were included representing the cultivated potato taxa. Heterozygosity ranged from 9.7% to 66.6% increasing with ploidy level with an average heterozygosity of 33.5%. Identity, relatedness, and ancestry were evaluated using hierarchal clustering and model-based Bayesian admixture analyses. Errors in genetic identity were revealed in a side-by-side comparison of in vitro clonal material with the original mother plants revealing mistakes putatively occurring during decades of processing and handling. A phylogeny was constructed to evaluate inter- and intraspecific relationships which together with a STRUCTURE analysis supported both commonly used treatments of potato taxonomy. Accessions generally clustered based on taxonomic and ploidy classifications with some exceptions but did not consistently cluster by geographic origin. STRUCTURE analysis identified putative hybrids and suggested six genetic clusters in the cultivated potato collection with extensive gene flow occurring among the potato populations, implying most populations readily shared alleles and that introgression is common in potato. Solanum tuberosum subsp. andigena (ADG) and S. curtilobum (CUR) displayed significant admixture. ADG likely has extensive admixture due to its broad geographic distribution. Solanum phureja (PHU), Solanum chaucha (CHA)/Solanum stenotomum subsp. stenotomum (STN), and Solanum tuberosum subsp. tuberosum (TBR) populations had less admixture from an accession/population perspective relative to the species evaluated. A core and mini core subset from the genebank material was also constructed. SNP genotyping was also carried out on 745 accessions from the Seed Savers potato collection which confirmed no genetic duplication between the two potato collections, suggesting that the collections hold very different genetic resources of potato. The Infinium SNP Potato Array is a powerful tool that can provide diversity assessments, fingerprint genebank accessions for quality management programs, use in research and breeding, and provide insights into the complex genetic structure and hybrid origin of the diversity present in potato genetic resource collections.

OcBSA: An NGS-based bulk segregant analysis tool for outcross populations

Constructing inbred lines for self-incompatible species and species with long generation times is challenging, making the use of F1 outcross/segregating populations the main strategy for genetic studies of such species. However, there is a lack of dedicated algorithms/tools for rapid quantitative trait locus (QTL) mapping using the F1 populations. To this end, we have designed and developed an algorithm/tool called OcBSA specifically for QTL mapping of F1 populations. OcBSA transforms the four-haplotype inheritance problem from the two heterozygous diploid parents of the F1 population into the two-haplotype inheritance problem common in current genetic studies by removing the two haplotypes from the heterozygous parent that do not contribute to phenotype segregation in the F1 population. Testing of OcBSA on 1800 simulated F1 populations demonstrated its advantages over other currently available tools in terms of sensitivity and accuracy. In addition, the broad applicability of OcBSA was validated by QTL mapping using seven reported F1 populations of apple, pear, peach, citrus, grape, tea, and rice. We also used OcBSA to map the QTL for flower color in a newly constructed F1 population of potato generated in this study. The OcBSA mapping result was verified by the insertion or deletion markers to be consistent with a previously reported locus harboring the ANTHOCYANIN 2 gene, which regulates potato flower color. Taken together, these results highlight the power and broad utility of OcBSA for QTL mapping using F1 populations and thus a great potential for functional gene mining in outcrossing species. For ease of use, we have developed both Windows and Linux versions of OcBSA, which are freely available at: https://gitee.com/Bioinformaticslab/OcBSA.

Characterization of a segregating potato (Solanum tuberosum L.) population for frost tolerance by leaf morpho-anatomy analysis and horticultural traits in India

Characterization of a segregating potato (Solanum tuberosum L.) population for frost tolerance by leaf morpho-anatomy analysis and horticultural traits in India

PolyGBLUP: a modified genomic best linear unbiased prediction improved the genomic prediction efficiency for autopolyploid species.

Given the universality of autopolyploid species in nature, it is crucial to develop genomic selection methods that consider different allele dosages for autopolyploid breeding. However, no method has been developed to deal with autopolyploid data regardless of the ploidy level. In this study, we developed a modified genomic best linear unbiased prediction (GBLUP) model (polyGBLUP) through constructing additive and dominant genomic relationship matrices based on different allele dosages. polyGBLUP could carry out genomic prediction for autopolyploid species regardless of the ploidy level. Through comprehensive simulations and analysis of real data of autotetraploid blueberry and guinea grass and autohexaploid sweet potato, the results showed that polyGBLUP achieved higher prediction accuracy than GBLUP and its superiority was more obvious when the ploidy level of autopolyploids is high. Furthermore, when the dominant effect was added to polyGBLUP (polyGDBLUP), the greater the dominance degree, the more obvious the advantages of polyGDBLUP over the diploid models in terms of prediction accuracy, bias, mean squared error and mean absolute error. For real data, the superiority of polyGBLUP over GBLUP appeared in blueberry and sweet potato populations and a part of the traits in guinea grass population due to the high correlation coefficients between diploid and polyploidy genomic relationship matrices. In addition, polyGDBLUP did not produce higher prediction accuracy than polyGBLUP for most traits of real data as dominant genetic variance was not captured for these traits. Our study will be a significant promising method for genomic prediction of autopolyploid species.

A FRACTIONAL DIFFERENTIAL EQUATION MODEL FOR THE SPREAD OF POTATO LEAF ROLL VIRUS (PLRV) ON POTATOES

Potatoes infected with the PLRV virus will experience a decrease in production up to 90%. In this paper, The PLRV distribution fractional differential equation model with potato and vector populations is reformulated by adding one new parameter, namely the rate of vector death due to predators. The model is divided into susceptible and infected classes. The PLRV dispersion model was developed and converted to a fractional order form for 0<σ ≤ 1. Next, the invariant region, positive solutions, basic reproduction number, equilibrium point, and stability were determined. Based on the stability analysis, it is shown that the stability of the disease-free equilibrium point is locally stable and globally stable if the basic reproduction number (R0)<1, and the stability of the endemic equilibrium point is globally stable if the basic reproduction number (R0)>1. Numerical solutions were also carried out to determine the effect of several parameters on the PLRV distribution model on potatoes. The numerical solution results show that the elimination rate of infected potatoes and the infection rate of potatoes have a significant role in controlling the spread of PLRV in potatoes.

A Genome Wide Association Study (GWAS) Identifies SNPs Associated with Resistance to Tobacco Rattle Virus (TRV) and Potato Mop-Top Virus (PMTV) in a Tetraploid Mapping Population of Potato

A Genome Wide Association Study (GWAS) Identifies SNPs Associated with Resistance to Tobacco Rattle Virus (TRV) and Potato Mop-Top Virus (PMTV) in a Tetraploid Mapping Population of Potato

Possible Reasons Affecting Different Phytophthora infestans Populations in Tomato and Potato Isolates in Thailand

Late blight, caused by the oomycete Phytophthora infestans, is one of the most important diseases affecting tomato and potato production worldwide. In Thailand, the disease is widespread in the north and northeast, especially in the Chiang-Mai and Tak provinces. The mating type, metalaxyl sensitivity, mitochondrial DNA (mtDNA) haplotype, RG57 fingerprinting, and microsatellite were used to characterize the P. infestans populations. The study revealed that the P. infestans of tomato isolates in Thailand are of the same lineage as those from 1994 until 2002. The clonal lineages that were found in the potato populations have changed since 1994. The changes in P. infestans isolates in the potato populations have likely been the result of the import of seed potatoes to Thailand. Furthermore, the P. infestans populations in potatoes show resistance to metalaxyl, whereas those from tomato isolates show sensitivity to fungicides. The reasons for the different responses can be attributed to (i) the use of metalaxyl, (ii) the host preferences of P. infestans, and (iii) the migration of new genotypes from infected potato seeds.

Identification of QTL associated with plant vine characteristics and infection response to late blight, early blight, and Verticillium wilt in a tetraploid potato population derived from late blight-resistant Palisade Russet.

Potato late blight (causal agent Phytophthora infestans) is a disease of potatoes with economic importance worldwide. Control is primarily through field monitoring and the application of fungicides. Control of late blight with fungicides and host plant resistance is difficult, with documented cases of such control measures failing with the advent of new pathotypes of P. infestans. To better understand host plant resistance and to develop more durable late blight resistance, Quantitative Trait Locus/Loci (QTL) analysis was conducted on a tetraploid mapping population derived from late blight-resistant potato cultivar Palisade Russet. Additionally, QTL analyses for other traits such as Verticillium wilt and early blight resistance, vine size and maturity were performed to identify a potential relationship between multiple traits and prepare genetic resources for molecular markers useful in breeding programs. For this, one hundred ninety progenies from intercrossing Palisade Russet with a late blight susceptible breeding clone (ND028673B-2Russ) were assessed. Two parents and progenies were evaluated over a two-year period for response to infection by the US-8 genotype of P. infestans in inoculated field screenings in Corvallis, Oregon. In Aberdeen, Idaho, the same mapping population was also evaluated for phenotypic response to early blight and Verticillium wilt, and vine size and maturity in a field over a two-year period. After conducting QTL analyses with those collected phenotype data, it was observed that chromosome 5 has a significant QTL for all five traits. Verticillium wilt and vine maturity QTL were also observed on chromosome 1, and vine size QTL was also found on chromosomes 3 and 10. An early blight QTL was also detected on chromosome 2. The QTL identified in this study have the potential for converting into breeder-friendly molecular markers for marker-assisted selection.

Prediction of genetic gains in sweet potato genotypes by polycross

Sweet potato crops present a wide genetic diversity, but genetic parameters of populations should be estimated in breeding programs, mainly when the selection is focused on multiple traits. Thus, the objective of this study was to estimate genetic parameters and select clones via a selection index in a sweet potato population obtained from uncontrolled crosses. The experiment was carried out in Ilha Solteira, Sao Paulo, Brazil, from June to November 2020, to evaluate 144 clones and three controls, totaling 147 treatments. A randomized block design was used, with two replications and three plants per plot. The data were analyzed through mixed modeling (REML/BLUP), and the selection index proposed by Mulamba & Mock was applied using a selection pressure of 17.3% for the selection of superior clones. The direct selection enabled a higher prediction of gains for each trait, but the joint analysis maximized the selection gains for all traits of interest. Clones 38, 63, 79, 77, and 5 are recommended, among the selected clones, for further stages of sweet potato breeding focused on improving traits for production and table consumption. Palavras-chave: Ipomoea batatas (L.) Lam, Variabilidade genética, Índice de seleção, Parâmetros genéticos, Ganho com seleção

Genetic Diversity and Population Structure Analysis of Potato Somaclones

Cultivated potato varieties are tetraploid and vegetatively propagated. Therefore genetic improvement for new traits is less effective through hybridization. The mutation is considered an alternative method for crop improvement of those varieties. This study aimed to evaluate the effects of gamma-ray irradiation on increasing genetic diversity among the somaclones and the changes in population structure. Forty-four somaclones were used as observed materials. The population was grown in a screen house using a completely randomized design with genotype (somaclone) as a single factor. Thirteen qualitatively and quantitatively morphological characters were observed. Six SSR markers were used for analyzing the population structure. The selection process was based on a weighting method divided into quartiles. Selected numbers were taken from quartile 3. Morphological analysis of stems and leaves resulted in five different somaclones, with significant differences in anthocyanin appearance and intensity of the green color of the leaflets. Diversity criteria based on quantitative characteristics showed a high level of diversity with a high heritability for tuber weight, length, and diameter and a moderate heritability for tuber number. Analyzing the population structure has offered insight into how gamma irradiation affected the somaclones. As a result of the selection, 12 somaclones met the requirements to serve as seed sources for field testing. It is expected that the results of this study will provide information about the diversity caused by gamma-ray irradiation treatment on potato somaclones and a method for improving the efficiency of the initial selection of potato populations.

High-Density Linkage Map Constructed from a Skim Sequenced Diploid Potato Population Reveals Transmission Distortion and QTLs for Tuber Yield and Pollen Shed

The reinvention of potato, from a tetraploid clonal crop into a diploid seed-based hybrid crop, requires insight in the mutational load, recombination landscape, and the genetic basis of fertility. Genomics-based breeding and QTL discovery rely on efficient genotyping strategies such as skim sequencing, to gather genotypic information. The application of skim sequencing to full-sib population of non-inbred parents remains challenging. Here, we report on an R implementation of the OutcrossSeq pipeline for diploids. We applied this pipeline to a large diploid skim sequenced potato population. We used the resulting bin-markers for the construction of high-density parent specific linkage maps, highlighting variation in parental recombination rate and structural variations. We subsequently explored transmission ratio distortion and non-independent assortment of alleles, indicative of large-effect deleterious mutations. Finally, we identified QTLs for seedling tuber yield in pots and pollen shed. This study showcases the range of genetic analyses, from marker inference, identification of transmission ratio distortion, and linkage map construction to QTL mapping, resulting in new insights that contribute to breeding diploid potato.

Investigating the genetic components of tuber bruising in a breeding population of tetraploid potatoes

BackgroundTuber bruising in tetraploid potatoes (Solanum tuberosum) is a trait of economic importance, as it affects tubers’ fitness for sale. Understanding the genetic components affecting tuber bruising is a key step in developing potato lines with increased resistance to bruising. As the tetraploid setting renders genetic analyses more complex, there is still much to learn about this complex phenotype. Here, we used capture sequencing data on a panel of half-sibling populations from a breeding programme to perform a genome-wide association analysis (GWAS) for tuber bruising. In addition, we collected transcriptomic data to enrich the GWAS results. However, there is currently no satisfactory method to represent both GWAS and transcriptomics analysis results in a single visualisation and to compare them with existing knowledge about the biological system under study.ResultsWhen investigating population structure, we found that the STRUCTURE algorithm yielded greater insights than discriminant analysis of principal components (DAPC). Importantly, we found that markers with the highest (though non-significant) association scores were consistent with previous findings on tuber bruising. In addition, new genomic regions were found to be associated with tuber bruising. The GWAS results were backed by the transcriptomics differential expression analysis. The differential expression notably highlighted for the first time the role of two genes involved in cellular strength and mechanical force sensing in tuber resistance to bruising. We proposed a new visualisation, the HIDECAN plot, to integrate the results from the genomics and transcriptomics analyses, along with previous knowledge about genomic regions and candidate genes associated with the trait.ConclusionThis study offers a unique genome-wide exploration of the genetic components of tuber bruising. The role of genetic components affecting cellular strength and resistance to physical force, as well as mechanosensing mechanisms, was highlighted for the first time in the context of tuber bruising. We showcase the usefulness of genomic data from breeding programmes in identifying genomic regions whose association with the trait of interest merit further investigation. We demonstrate how confidence in these discoveries and their biological relevance can be increased by integrating results from transcriptomics analyses. The newly proposed visualisation provides a clear framework to summarise of both genomics and transcriptomics analyses, and places them in the context of previous knowledge on the trait of interest.

Molecular Marker-Assisted Selection for Frost Tolerance in a Diallel Population of Potato.

A multi-parental population is an innovative tool for mapping large numbers of loci and genetic modifications, particularly where they have been used for breeding and pre-breeding in crops. Frost injury is an environmental stress factor that greatly affects the growth, development, production efficiency, and geographical distribution of crops. No reported study has focused on genetic mapping and molecular marker development using diallel populations of potatoes. In this study, 23 successful cross combinations, obtained by a half diallel cross among 16 parents, including eight frost-tolerant advanced breeding lines and eight cultivars, were used to map the genetic loci for frost tolerance and to create a molecular marker-assisted selection (MAS) system. Three candidate regions related to frost tolerance on chromosomes II, V, and IX were mapped by bulked segregant analysis (BSA). Furthermore, six SNP markers associated with frost tolerance from candidate regions were developed and validated. Above all, a MAS system for the frost tolerance screening of early breeding offspring was established. This study highlights the practical advantages of applying diallel populations to broaden and improve frost-tolerant germplasm resources.

Glycoalkaloid Composition and Flavonoid Content as Driving Forces of Phytotoxicity in Diploid Potato.

Despite their advantages, biotechnological and omic techniques have not been applied often to characterize phytotoxicity in depth. Here, we show the distribution of phytotoxicity and glycoalkaloid content in a diploid potato population and try to clarify the source of variability of phytotoxicity among plants whose leaf extracts have a high glycoalkaloid content against the test plant species, mustard. Six glycoalkaloids were recognized in the potato leaf extracts: solasonine, solamargine, α-solanine, α-chaconine, leptinine I, and leptine II. The glycoalkaloid profiles of the progeny of the group with high phytotoxicity differed from those of the progeny of the group with low phytotoxicity, which stimulated mustard growth. RNA sequencing analysis revealed that the upregulated flavonol synthase/flavonone 3-hydroxylase-like gene was expressed in the progeny of the low phytotoxicity group, stimulating plant growth. We concluded that the metabolic shift among potato progeny may be a source of different physiological responses in mustard. The composition of glycoalkaloids, rather than the total glycoalkaloid content itself, in potato leaf extracts, may be a driving force of phytotoxicity. We suggest that, in addition to glycoalkaloids, other metabolites may shape phytotoxicity, and we assume that these metabolites may be flavonoids.

Tuber skin colour variation in the segregating populations of potatoes (Solanum tuberosum L.)

Tuber skin colour variation in the segregating populations of potatoes (Solanum tuberosum L.)

Molecular markers as tools in breeding for resistance to Potato Virus Y

Potato virus Y (PVY) is an economically important pathogen of potato as a vegetatively propagated crop. High resistance to all strains of PVY is determined by Ry-genes, which are introgressed into modern potato varieties from a limited number of sources of resistance ‒ Solanum stoloniferum Schlechtd. et Bche., Solanum andigenum Juz. et Buk., Solanum chacoense Bitt. Use of new species Solanum and interspecific hybrids based on them provides for the expansion of existing potato gene pool in breeding for resistance to PVY. Traditional breeding for resistance to viruses has still a great potential, though, it is a long and laborious process. Molecular markers linked to Ry-genes are widely integrated in order to increase the effectiveness of practical breeding. Previous studies have revealed a number of shortcomings in using the molecular markers of Ry-genes. To assess the predictive abilities of molecular markers RYSC3, M45, M6 of the Ryadg gene and YES3-3A of the Rysto gene for resistance to PVY, the F1 generation of two potato populations was studied, in the creation of which inter-specific hybrids were used. The nature of segregation 5:3 obtained by phenotype showed that the original parental forms can be the sources of not only previously identified, but also unidentified Ry-genes and Ny-genes of hypersensitivity. Correlation coefficient between the presence of markers and resistance to PVY was 0.64 for the YES3-3 marker (79 % matching) and 0.54 for RYSC3, М45, М6 markers (76 % matching). There have been revealed the cases of “false positive” results of the study (the presence of a marker in susceptible genotypes), which indicate to the insufficient effectiveness of the markers used. The marker segregation observed in the populations was consistent with chromatid segregation, confirming the simplex nature of Ry-genes inheritance from resistant parents. The ratio of genotypes with the presence/absence of markers was 0.86:1.