Potato Germplasm Research Articles

Elucidating the molecular basis of salt tolerance in potatoes through miRNA expression and phenotypic analysis

Potatoes are a critical staple crop worldwide, yet their yield is significantly constrained by salt stress. Understanding and enhancing salt tolerance in potatoes is crucial for ensuring food security. This study evaluated the salt tolerance of 17 diverse potato varieties using principal component analysis, membership function analysis, cluster analysis, and stepwise regression analysis. Comprehensive evaluation based on morphological, physiological, and biochemical indicators divided the varieties into three categories, identifying Z1264-1, Z700-1, Z943-1, Z1266-1, Z510-1, and Z1076-1 as having strong salt tolerance. Regression equations established stem thickness, root length, and catalase activity as rapid identification markers for salt tolerance in tetraploid potatoes. Transcriptome analysis of the highly tolerant variety Z1076-1 identified 68 differentially expressed miRNAs (DE miRNAs). qRT-PCR validation for eight randomly selected DE miRNAs confirmed consistent expression trends with transcriptome data. Predicted target genes of these miRNAs are involved in calcium channel signaling, osmotic regulation, plant hormone signaling, and reactive oxygen species clearance. Our findings provide valuable insights for the identification and screening of salt-tolerant potato germplasms. The findings also lay the foundation for studying molecular mechanisms of salt tolerance and advancing genetic breeding efforts to cultivate more resilient potato varieties.

Determination of processing quality of local potato germplasms for industrial use

Potato (Solanum tuberosum L.) of the family Solanaceae is ranked globally as the fourth most important crop after rice, maize, and wheat. More than 7,500 different varieties of potato are found around the globe. In Pakistan the total area under potatoes cultivation is 134300 ha with production of about 2.5 million tons/annum. The availability of fresh and nutritive potatoes for human utilization is very essential. The present study was conducted to screen thirty-six potato genotypes for processing quality characteristics including specific gravity, dry matter and ash contents to determine their suitability for industrial use in compliance with food safety standards. The purpose of this study was to identify the new and best processing varieties considered suitable for industrial use and to recommend such varieties to the farmers for further growth. Among the thirty-six potato genotypes, 393594-72 (1.080 g/cm3), Kuroda (1.083 g/cm3), Potato-III (1.085 g/cm3) and Romeo (1.095 g/cm3) has the highest specific gravity, whereas Sarpomira (20.13%), 393574-72 (20.21%), Kuroda (21.1%), Potato-III (21.25%), and Romeo (23.38%) was found superior for their dry matter. The maximum ash contents were recorded in Sturna (6.65%) followed by Zia-III (5.55%). Most of the potatoes cultivars at any location produced tubers with a dry matter content greater than 18.0% and a specific gravity of 1.070 g/cm3, which are within the acceptable range for processing. The study was helpful in evaluation of best potato genotypes for industrial purposes and their cultivation by the farmers.

Genome-Wide Association Study of Sweet Potato Storage Root Traits Using GWASpoly, a Gene Dosage-Sensitive Model.

Sweet potato (Ipomoea batatas) is an important food crop that plays a pivotal role in preserving worldwide food security. Due to its polyploid genome, high heterogeneity, and phenotypic plasticity, sweet potato genetic characterization and breeding is challenging. Genome-wide association studies (GWASs) can provide important resources for breeders to improve breeding efficiency and effectiveness. GWASpoly was used to identify 28 single nucleotide polymorphisms (SNPs), comprising 21 unique genetic loci, associated with sweet potato storage root traits including dry matter (4 loci), subjective flesh color (5 loci), flesh hue angle (3 loci), and subjective skin color and skin hue angle (9 loci), in 384 accessions from the USDA sweet potato germplasm collection. The I. batatas 'Beauregard' and I. trifida reference genomes were utilized to identify candidate genes located within 100 kb from the SNPs that may affect the storage traits of dry matter, flesh color, and skin color. These candidate genes include transcription factors (especially Myb, bHLH, and WRKY family members), metabolite transporters, and metabolic enzymes and associated proteins involved in starch, carotenoid, and anthocyanin synthesis. A greater understanding of the genetic loci underlying sweet potato storage root traits will enable marker-assisted breeding of new varieties with desired traits. This study not only reinforces previous research findings on genes associated with dry matter and β-carotene content but also introduces novel genetic loci linked to these traits as well as other root characteristics.

Allelopathic Molecular Mechanisms of the Two Main Allelochemicals in Sweet Potato.

Sweet potato (Ipomoea batatas L.) is one of the most important global food crops. This crop exhibits excellent allelopathic potential against various weeds, but its allelopathic mechanism at the molecular level is unclear. Therefore, metabolomic and transcriptomic analyses were performed to explore the allelopathic effects, metabolic pathway, and associated genes for two major compounds with allelopathic activity, palmitic acid and linoleic acid. The sweet potato variety Ningshu 25 was employed in the current study. The results showed that palmitic acid and linoleic acid had strong allelopathic effects on seed germination, plant growth, antioxidant enzyme activity, and chlorophyll content of two weeds Digitaria sanguinalis and Bidens pilosa. The content of the two targeted metabolites was affected by different environmental conditions and was significantly increased under low temperature (15 °C). Five metabolic pathways involved in the two targeted metabolites of fatty acids were found: fatty acid biosynthesis, fatty acid elongation, fatty acid degradation, biosynthesis of cutin, suberine, and wax, and the linoleic acid metabolism pathway. The synthesis of palmitic acid is significantly enriched in the biosynthesis pathways of fatty acids, cutin, suberine, and wax, and the synthesis of linoleic acid is significantly enriched in the linoleic acid metabolism pathway. Under different environmental conditions, there were three key genes expressed-g4988, g11881, and g19673-located in the biosynthesis pathways of cutin, suberine, and wax; four key genes expressed-g31191, g60956, g49811, and g59542-located in the biosynthesis pathway of fatty acids; and six key expressed genes-g26575, g24787, g23517, g57649, g58562, and g4314-located in biosynthesis pathway of linoleic acid, respectively. Our study advances understanding of the molecular mechanisms behind allelopathic traits in sweet potato and provides a set of candidate genes for use in improving allelopathic potential in sweet potato germplasm resources.

Defense strategies against sweet potato chlorotic stunt and pakakuy virus coinfection unraveled

AbstractThis study into the response of two Ipomoea batatas (L.) Lam cultivars, Melinda and Tio Joe, to coinfection with sweet potato chlorotic stunt virus (SPCSV) and sweet potato pakakuy virus (SPPV), employed a comprehensive approach encompassing symptomatology, real‐time quantitative polymerase chain reaction, metagenomics, and transcriptomics. SPCSV is a quarantine virus with synergistic effects, which decimate yields. SPPV is the most prevalent DNA virus in sweet potato germplasm, with a tendency to persist in meristems, posing a significant risk for germplasm transfer between territories. Graft inoculation experiments revealed that while Tio Joe remained asymptomatic for 12 weeks and suppressed virus replication, Melinda displayed symptoms early on and exhibited high virus titers. Metagenomic analyses corroborated these observations and confirmed that SPCSV and SPPV were responsible. Transcriptomic analysis unveiled disparities in gene expression between Melinda and Tio Joe. Differential gene expression was heightened and altered in Melinda as the viruses disrupted its gene expression. Its defense strategies, such as inducing abscisic acid signaling, were insufficient to overcome disruptive viral effects like oxidative stress, rendering it susceptible. In contrast, Tio Joe had relatively stable differential gene expression, indicating resistance to SPPV–SPCSV coinfection. Overexpressed genes such as sirtuin, rapid alkalization factor, and nuclear pore anchor triggered quantitative resistance, supported with enriched organelles such as mitochondrion and pathways such as proteasome and cutin, suberine, and wax biosynthesis. Tio Joe maintained its genome integrity and inhibited viral replication by tightly controlling gene expression and preventing reactive oxygen species accumulation.

Identification of drought resistance and screening of evaluation indexes of 80 potato germplasm resources introduced by CIP

Identification of drought resistance and screening of evaluation indexes of 80 potato germplasm resources introduced by CIP

Screening of potato germplasm for resistance to potato virus y and potato leafroll virus using DAS-ELISA

Potato (Solanum tuberosum L.) ranks as the fourth most important staple food globally, after rice, wheat, and maize. In Pakistan, Potato virus Y (PVY) and Potato leafroll virus (PLRV) are among the most critical pathogens affecting potato crops, causing yield losses of up to 90%. Fifteen advanced potato lines from the Potato Program of the Horticultural Research Institute (HRI) were screened for resistance to these economically significant viruses. The experiment was conducted in the glasshouse of the Crop Diseases Research Institute, NARC, Islamabad, during 2023-24, following a completely randomized design with three replications per clone. For screening, small tubers of fifteen potato clones, including one check variety, were planted in pots within the glasshouse. PVY was mechanically transmitted, while a chip graft inoculation assay was used for screening against PLRV. Symptoms began to appear two weeks after inoculation, and data were recorded four weeks post-inoculation. A double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) was performed on all plants to confirm the presence of both viruses serologically. The findings revealed that the line HRI-P1 remained asymptomatic and was categorized as highly resistant to both viruses, based on symptom observation and ELISA testing. Six clones exhibited varying levels of resistance, three showed moderate susceptibility, one was susceptible, and three were highly susceptible to PVY. The study highlights the availability of valuable sources of resistance within the Potato Program. HRI, NARC, which could be utilized in breeding potential future varieties. The disease-resistant genotypes identified will be instrumental in future potato breeding programs.

Haplotype-resolved genome and mapping of freezing tolerance in the wild potato Solanum commersonii.

Solanum commersonii (2n = 2x = 24, 1EBN, Endosperm Balance Number), native to the southern regions of Brazil, Uruguay, and northeastern Argentina, is the first wild potato germplasm collected by botanists and exhibits a remarkable array of traits related to disease resistance and stress tolerance. In this study, we present a high-quality haplotype-resolved genome of S. commersonii. The two identified haplotypes demonstrate chromosome sizes of 706.48 and 711.55Mb, respectively, with corresponding chromosome anchoring rates of 94.2 and 96.9%. Additionally, the contig N50 lengths are documented at 50.87 and 45.16Mb. The gene annotation outcomes indicate that the haplotypes encompasses a gene count of 39 799 and 40 078, respectively. The genome contiguity, completeness, and accuracy assessments collectively indicate that the current assembly has produced a high-quality genome of S. commersonii. Evolutionary analysis revealed significant positive selection acting on certain disease resistance genes, stress response genes, and environmentally adaptive genes during the evolutionary process of S. commersonii. These genes may be related to the formation of diverse and superior germplasm resources in the wild potato species S. commersonii. Furthermore, we utilized a hybrid population of S. commersonii and S. verrucosum to conduct the mapping of potato freezing tolerance genes. By combining BSA-seq analysis with traditional QTL mapping, we successfully mapped the potato freezing tolerance genes to a specific region on Chr07, spanning 1.25Mb, with a phenotypic contribution rate of 18.81%. In short, current research provides a haplotype-resolved reference genome of the diploid wild potato species S. commersonii and establishes a foundation for further cloning and unraveling the mechanisms underlying cold tolerance in potatoes.

Root Infection and Minituber Yield Response to Powdery Scab in Plant Growth Chamber Conditions

Powdery scab, caused by the soil borne Plasmodiophorid Spongospora subterranea f. sp. subterranea (Sss), is an increasing concern. Developing resistant varieties with enduring resistance is crucial for sustainable disease management. However, the lack of a consistent infection assay for Sss hindered effective evaluation of disease symptoms, including root gall formation and tuber lesions. This study introduces a reliable method for assessing Sss pathogenicity using a sand/potting mixture in a controlled-environment plant growth chamber. Potato plants were inoculated with three types of inocula sourced from root galls, infested soil, and scab-like tube lesions. All inocula successfully induced root galls and tuber lesions, with the tuber lesion-derived inoculum producing the highest number of root galls. Additionally, the method demonstrated a marked impact on tuber yield, weight, and size in both highly susceptible and moderately susceptible cultivars. These findings underscore the efficacy of this infection assay as a robust tool for evaluating Sss pathogenicity. This method holds promise for screening potato germplasm to develop resistant varieties against powdery scab.

Genotyping-by-sequencing targets genic regions and improves resolution of genome-wide association studies in autotetraploid potato

Key messageDe novo genotyping in potato using methylation-sensitive GBS discovers SNPs largely confined to genic or gene-associated regions and displays enhanced effectiveness in estimating LD decay rates, population structure and detecting GWAS associations over ‘fixed’ SNP genotyping platform. Study also reports the genetic architectures including robust sequence-tagged marker–trait associations for sixteen important potato traits potentially carrying higher transferability across a wider range of germplasm.This study deploys recent advancements in polyploid analytical approaches to perform complex trait analyses in cultivated tetraploid potato. The study employs a ‘fixed’ SNP Infinium array platform and a ‘flexible and open’ genome complexity reduction-based sequencing method (GBS, genotyping-by-sequencing) to perform genome-wide association studies (GWAS) for several key potato traits including the assessment of population structure and linkage disequilibrium (LD) in the studied population. GBS SNPs discovered here were largely confined (~ 90%) to genic or gene-associated regions of the genome demonstrating the utility of using a methylation-sensitive restriction enzyme (PstI) for library construction. As compared to Infinium array SNPs, GBS SNPs displayed enhanced effectiveness in estimating LD decay rates and discriminating population subgroups. GWAS using a combined set of 30,363 SNPs identified 189 unique QTL marker–trait associations (QTL-MTAs) covering all studied traits. The majority of the QTL-MTAs were from GBS SNPs potentially illustrating the effectiveness of marker-dense de novo genotyping platforms in overcoming ascertainment bias and providing a more accurate correction for different levels of relatedness in GWAS models. GWAS also detected QTL ‘hotspots’ for several traits at previously known as well as newly identified genomic locations. Due to the current study exploiting genome-wide genotyping and de novo SNP discovery simultaneously on a large tetraploid panel representing a greater diversity of the cultivated potato gene pool, the reported sequence-tagged MTAs are likely to have higher transferability across a wider range of potato germplasm and increased utility for expediting genomics-assisted breeding for the several complex traits studied.

Screening of Drought-Resistant Potato Germplasm Resources Based on Intelligent Algorithm

As a staple food resource, potato is of great significance for improving grain reserves and ensuring national food security. In order to improve potato yield and promote the process of potato becoming a staple food, a K-means algorithm optimized by particle swarm algorithm was proposed to realize the screening of dry potato germplasm resources. First, the research continues the research on particle swarm optimization, and innovatively applies K-means algorithm to optimization. The research utilizes the advantages of particle swarm optimization, such as fast convergence speed, strong search ability, and simple operation, to enable particle swarm optimization to take on the role of optimizing the initial clustering center, thereby improving the accuracy and efficiency of clustering analysis. On this basis, a PSO-K-means drought resistant potato germplasm resource screening model was constructed. This model consists of a data collection and preprocessing module, an impact indicator determination module, and a comprehensive evaluation module. Finally, the application effect of the model was verified. The results show that the AUC value of the model is up to 0.840, and the screening accuracy is as high as 94.5%, which is 13.5% higher than that of the K-means model. The research method has been validated to improve the limitations of K-means mode, such as high screening error, weak stability, and falling into local optimal solutions. It optimizes the screening effect of drought resistant potato germplasm resources, which is conducive to exploring the potential of potato resources. In addition, research has also provided broader ideas for the optimization and application of particle swarm optimization algorithms.

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.

Development and Validation of Near-Infrared Reflectance Spectroscopy Prediction Modeling for the Rapid Estimation of Biochemical Traits in Potato.

Potato is a globally significant crop, crucial for food security and nutrition. Assessing vital nutritional traits is pivotal for enhancing nutritional value. However, traditional wet lab methods for the screening of large germplasms are time- and resource-intensive. To address this challenge, we used near-infrared reflectance spectroscopy (NIRS) for rapid trait estimation in diverse potato germplasms. It employs molecular absorption principles that use near-infrared sections of the electromagnetic spectrum for the precise and rapid determination of biochemical parameters and is non-destructive, enabling trait monitoring without sample compromise. We focused on modified partial least squares (MPLS)-based NIRS prediction models to assess eight key nutritional traits. Various mathematical treatments were executed by permutation and combinations for model calibration. The external validation prediction accuracy was based on the coefficient of determination (RSQexternal), the ratio of performance to deviation (RPD), and the low standard error of performance (SEP). Higher RSQexternal values of 0.937, 0.892, and 0.759 were obtained for protein, dry matter, and total phenols, respectively. Higher RPD values were found for protein (3.982), followed by dry matter (3.041) and total phenolics (2.000), which indicates the excellent predictability of the models. A paired t-test confirmed that the differences between laboratory and predicted values are non-significant. This study presents the first multi-trait NIRS prediction model for Indian potato germplasm. The developed NIRS model effectively predicted the remaining genotypes in this study, demonstrating its broad applicability. This work highlights the rapid screening potential of NIRS for potato germplasm, a valuable tool for identifying trait variations and refining breeding strategies, to ensure sustainable potato production in the face of climate change.

Genotyping-by-sequencing and weighted gene co-expression network analysis of genes responsive against Potato virus Y in commercial potato cultivars.

Potato is considered a key component of the global food system and plays a vital role in strengthening world food security. A major constraint to potato production worldwide is the Potato Virus Y (PVY), belonging to the genus Potyvirus in the family of Potyviridae. Selective breeding of potato with resistance to PVY pathogens remains the best method to limit the impact of viral infections. Understanding the genetic diversity and population structure of potato germplasm is important for breeders to improve new cultivars for the sustainable use of genetic materials in potato breeding to PVY pathogens. While, genetic diversity improvement in modern potato breeding is facing increasingly narrow genetic basis and the decline of the genetic diversity. In this research, we performed genotyping-by-sequencing (GBS)-based diversity analysis on 10 commercial potato cultivars and weighted gene co-expression network analysis (WGCNA) to identify candidate genes related to PVY-resistance. WGCNA is a system biology technique that uses the WGCNA R software package to describe the correlation patterns between genes in multiple samples. In terms of consumption, these cultivars are a high rate among Iranian people. Using population structure analysis, the 10 cultivars were clustered into three groups based on the 118343 single nucleotide polymorphisms (SNPs) generated by GBS. Read depth ranged between 5 and 18. The average data size and Q30 of the reads were 145.98 Mb and 93.63%, respectively. Based on the WGCNA and gene expression analysis, the StDUF538, StGTF3C5, and StTMEM161A genes were associated with PVY resistance in the potato genome. Further, these three hub genes were significantly involved in defense mechanism where the StTMEM161A was involved in the regulation of alkalization apoplast, the StDUF538 was activated in the chloroplast degradation program, and the StGTF3C5 regulated the proteins increase related to defense in the PVY infected cells. In addition, in the genetic improvement programs, these hub genes can be used as genetic markers for screening commercial cultivars for PVY resistance. Our survey demonstrated that the combination of GBS-based genetic diversity germplasm analysis and WGCNA can assist breeders to select cultivars resistant to PVY as well as help design proper crossing schemes in potato breeding.

Calcium modulation of bacterial wilt disease on potato.

Ralstonia solanacearum species complex (RSSC) includes a diverse group of bacterial strains that cause bacterial wilt. This disease is difficult to control due to pathogen aggressiveness, persistence, wide range of hosts, and wide geographic distribution in tropical, subtropical, and temperate regions. RSSC causes considerable losses depending on the pathogen strain, host, soil type, environmental conditions, and cultural practices. In potato, losses of $19 billion per year have been estimated for this pathogen worldwide. In this study, we report for the first time the mineral composition found in xylem sap and plant tissues of potato germplasm with different levels of resistance to bacterial wilt. This study underscores the crucial role of calcium (Ca) concentration in the xylem sap and stem in relation to the resistance of different genotypes. Our in vitro experiments provide evidence of Ca's inhibitory effect on the growth, biofilm formation, and twitching movement of the model RSSC strain R. pseudosolanacearum GMI1000. This study introduces a novel element, the Ca concentration, which should be included into the integrated disease control management strategies for bacterial wilt in potatoes.

Morpho-Physiological Characterization of Potato (Solanum Tuberosum) Genotypes of the Andigenum and Phureja Group from the Working Collection of the Universidad De Nariño

This study presents the morpho-physiological characterization of potato (Solanum tuberosum) genotypes from the Andigenum and Phureja groups, cultivated at the Nariño, Colombia. The research addresses the vital role of genetic diversity in agricultural sustainability and food security, highlighting the importance of genetic resources for crop improvement and ecosystem stability. The study utilized a comprehensive morphological characterization based on both qualitative and quantitative descriptors to assess genetic variability within the university's potato collection. This approach allowed for the identification of duplicates, the enhancement of a morphological database, and insights into the genetic diversity of the collections. Using techniques like Multiple Correspondence Analysis (ACM) and Principal Component Analysis (PCA), distinct clusters of genotypes were identified, which were highly influenced by their ploidy levels. Results indicated significant morphological variation between diploid Phureja and tetraploid Andigenum genotypes. Phureja genotypes showed greater similarity among themselves compared to the more diverse Andigenum group. This morphological diversity is importante for the identification of specific traits beneficial for breeding programs, such as resistance to environmental stresses and diseases. The study underscores the importance of maintaining genetic diversity within potato germplasm collections, facilitating the selection of genotypes with desirable agronomic traits. The findings contribute significantly to the understanding of the genetic and morphological foundations necessary for the future genetic improvement of the potato, a staple food crop with profound implications for global food security. The geographic distribution of the genotypes also suggested a correlation between morphological traits and geographic locations, reinforcing the role of local adaptation in crop diversity and resilience.

The phased Solanum okadae genome and Petota pangenome analysis of 23 other potato wild relatives and hybrids

Potato is an important crop in the genus Solanum section Petota. Potatoes are susceptible to multiple abiotic and biotic stresses and have undergone constant improvement through breeding programs worldwide. Introgression of wild relatives from section Petota with potato is used as a strategy to enhance the diversity of potato germplasm. The current dataset contributes a phased genome assembly for diploid S. okadae, and short read sequences and de novo assemblies for the genomes of 16 additional wild diploid species in section Petota that were noted for stress resistance and were of interest to potato breeders. Genome sequence data for three additional genomes representing polyploid hybrids with cultivated potato, and an additional genome from non-tuberizing S. etuberosum, which is outside of section Petota, were also included. High quality short reads assemblies were achieved with genome sizes ranging from 575 to 795 Mbp and annotations were performed utilizing transcriptome sequence data. Genomes were compared for presence/absence of genes and phylogenetic analyses were carried out using plastome and nuclear sequences.

Breeding value of potato hybrid clones from the VIR collection revealed in the environments of Kamchatka Territory

Background. Potato breeding involves planned artificial hybridization between previously selected parental lines. A way to make potato breeding more efficient is to use the diversity of the germplasm and broaden the gene pool of parental lines. Interspecific potato hybrids originated on the elite potato germplasm display a set of valuable traits. The current challenge is to assess the performance of potato hybrids under specific soil and climate conditions to clarify their breeding value.The objective of the study was to evaluate potato hybrids in the environments of Kamchatka Territory according to a set of traits, identify the best parental lines, develop new hybrid combinations, and select promising breeding material.Materials and methods. Eleven potato hybrids from VIR were studied over three years (2020–2022) in the fields of Kamchatka Research Institute of Agriculture. The hybrids were benchmarked against two reference potato cultivars, ‘Fresco’ and ‘Vulkan’, belonging to the early and mid-early maturity groups, respectively. Crosses between the hybrids and 28 potato cultivars were carried out in the greenhouse. The new hybrid material was tested in a preliminary trial nursery for yield and earliness.Results. Hybrid 117-2 was better in yield (899 g/plant) than cvs. ‘Vulkan’ and ‘Fresco’ (700–739 g/plant). Hybrids 94-5, 99-10- 1, 8-1-2004, 8-3-2004, 8-5-2004, 135-3-2005, 135-5-2005, 99-6-6, and 134-2-2006 in most traits matched the potato cultivars, manifesting good berry formation and seed setting when crossed. Out of 140 crosses between 11 hybrids and 28 cultivars, 35 crosses between 10 hybrids and 13 cultivars were successful. Most hybrids were effectively used in crossings as maternal forms.Conclusion. VIR’s hybrids 94-5, 8-1-2004, and 8-5-2004 proved the most promising as source material for the development of new early potatoes under the conditions of Kamchatka Territory.

A survey of the Sli gene in wild and cultivated potato.

Inbred-hybrid breeding of diploid potatoes necessitates breeding lines that are self-compatible. One way of incorporating self-compatibility into incompatible cultivated potato (Solanum tuberosum) germplasm is to introduce the S-locus inhibitor gene (Sli), which functions as a dominant inhibitor of gametophytic self-incompatibility. To learn more about Sli diversity and function in wild species relatives of cultivated potato, we obtained Sli gene sequences that extended from the 5'UTR to the 3'UTR from 133 individuals from 22 wild species relatives of potato and eight diverse cultivated potato clones. DNA sequence alignment and phylogenetic trees based on genomic and protein sequences show that there are two highly conserved groups of Sli sequences. DNA sequences in one group contain the 533 bp insertion upstream of the start codon identified previously in self-compatible potato. The second group lacks the insertion. Three diploid and four polyploid individuals of wild species collected from geographically disjointed localities contained Sli with the 533 bp insertion. For most of the wild species clones examined, however, Sli did not have the insertion. Phylogenetic analysis indicated that Sli sequences with the insertion, in wild species and in cultivated clones, trace back to a single origin. Some diploid wild potatoes that have Sli with the insertion were self-incompatible and some wild potatoes that lack the insertion were self-compatible. Although there is evidence of positive selection for some codon positions in Sli, there is no evidence of diversifying selection at the gene level. In silico analysis of Sli protein structure did not support the hypothesis that amino acid changes from wild-type (no insertion) to insertion-type account for changes in protein function. Our study demonstrated that genetic factors besides the Sli gene must be important for conditioning a switch in the mating system from self-incompatible to self-compatible in wild potatoes.

Enhancing microspore embryogenesis in diploid potato (Solanum tuberosum L. ssp. tuberosum) germplasm

Doubled haploidy (DH) technology has been utilized in cultivated tetraploid potato (Solanum tuberosum L. ssp. tuberosum) to accelerate crop improvement; however very little work has been done with the diploid species. Experiments were undertaken to improve microspore embryogenic response in the diploid germplasm. Several factors influencing embryogenic responses were evaluated. An increase in calcium nitrate, a reduction in the plant growth regulators 6-benzyladenine (BA) and α-naphthaleneacetic acid (NAA), as well as an incubation temperature of 28 °C resulted in an increase in callus production and, in some cases, embryo-like structures. Validation of the modified protocol was conducted with both diploid and tetraploid potato germplasm with responses from both diploid and tetraploid. Monoploid and di-haploid plants were also regenerated from these microspore-derived calli.