Potato Breeding Research Articles

Evaluation of genetic diversity and genome-wide association studies of resistance to bacterial wilt disease in potato.

The development of novel improved varieties adapted to unstable environmental conditions is possible through the genetic diversity of breeding materials. Potato is among the most important food crops worldwide, however, there are still significant hindrances to breeding gains attributed to its autotetraploid and highly heterozygous genome. Bacterial wilt caused by the Ralstonia solanacearum species complex (RSSC) is an important disease affecting potato among many economically important crops worldwide. No cultivated potato genotypes have shown a satisfactory level of resistance to bacterial wilt. Nevertheless, resistance can play a crucial role in effective integrated disease management. To understand the genetic landscape of bacterial wilt resistance in cultivated potato, we evaluated the diversity of 194 accessions from the International Potato Centre (CIP) using 9,250 single nucleotide polymorphisms (SNPs) and their associations to the response to bacterial wilt disease evaluated over two independent trials. Twenty-four accessions showed high resistance throughout both trials. Genetic diversity analysis revealed three major clusters whose subgroups were mostly represented by CIP clones derived from common parents. Genome-wide association analyses have shown six major hits: two on chromosome 8, and one on each chromosome 2, 4, 5, and 9. These results facilitate genetic dissection of bacterial wilt resistance and marker-enabled breeding in elite genotypes for potato breeding initiatives.

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.

Early Generation Selection of Potato Breeding Lines

Potato is the third most important food crop in the world in terms of adaptability, yield potential, and nutritional advantages. This study aimed to conduct potato breeding work for cultivation in Kazakhstan; potato breeding for further processing into chips with cultivation in the northern regions; and the selection of potatoes for processing into frozen French fries with cultivation in the southern and south-eastern regions. Potato varieties (Fontane, Santana, and Punchy) were used as reference varieties to check molecular markers linked to maturity, tuber shape, and flesh color. A total of 42 potato breeding lines crossed from Yagodnyi 19 and CIP clone 397079-6 were used in this study to identify prospective breeding lines. The research was carried out between 2023 and 2024 and under greenhouse conditions. According to the results of molecular analysis and phenotypic data, 21 breeding lines were identified as prospective potato breeding lines. The majority of these potato breeding lines had a round tuber shape and were recommended for chip processing. Three breeding lines had a long oval tuber shape, making them suitable for French fries. Six breeding lines with short-oval and oval tuber shapes were found for consumer potato processing. It is recommended that the breeding process and studies of biochemical properties are continued in all of these identified potato breeding lines.

Influence of Storage Conditions on Four Chipping Potato Cultivars Developed in North Dakota

Cold temperature storage (lower than 10 °C) has been used as a management strategy to extend marketability and reduce potato storage losses. However, cold temperatures may result in dark-colored chips through a process known as cold-induced sweetening (CIS). ‘Dakota Crisp’ and ‘Dakota Diamond’ are two North Dakota State University potato breeding program cultivar releases selected for cold-chipping ability with high tuber yield potential. Two-year storage trials were conducted to examine sugar development and tuber processing quality of four cultivars grown at three nitrogen rates under irrigated and non-irrigated field conditions. The two-way interaction between storage period and storage temperature was significant for sucrose content, glucose content, visual chip color, and Agtron values, indicating a difference in sugar development for each storage temperature profile. Among the four cultivars evaluated under both irrigated and non-irrigated production conditions, ‘Dakota Pearl’ accumulated significantly less sucrose and glucose compared to other cultivars under the same storage conditions. ‘Dakota Crisp’ produced acceptable chip color from 8.9 °C after long term storage, while ‘Dakota Diamond’ produced acceptable chip color from 8.9 °C for up to 6 months of storage. These results emphasize the importance of developing cultivar-specific management profiles including storage and the informational need for producers and processors in determining the best practices for individual cultivars.

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.

Assembly and comparative analysis of the mitochondrial genome in diploid potatoes.

We report the mitochondrial genome of 39 diploid potatoes and identify a candidate ORF potentially linked to cytoplasmic male sterility in potatoes. Potato (Solanum tuberosum L.) holds a critical position as the foremost non-grain food crop, playing a pivotal role in ensuring global food security. Diploid potatoes constitute a vital genetic resource pool, harboring the potential to revolutionize modern potato breeding. Nevertheless, diploid potatoes are relatively understudied, and mitochondrial DNA can provide valuable insights into key potato breeding traits such as CMS. In this study, we examine and assemble the mitochondrial genome evolution and diversity of 39 accessions of diploid potatoes using high-fidelity (HiFi) sequencing. We annotated 54 genes for all the investigated accessions, comprising 34 protein-coding genes, 3 rRNA genes, and 17 tRNA genes. Our analyses revealed differences in repeats sequences between wild and cultivated landraces. To understand the evolution of diploid maternal lineage inheritance, we conducted phylogenetic analysis, which clearly distinguished mitochondrial from nuclear gene trees, further supporting the evidence-based of clustering between wild and cultivated landraces accessions. Our study discovers new candidate ORFs associated with CMS in potatoes, including ORF137, which is homologous to other CMS in Solanaceae. Ultimately, this work bridges the gap in mitochondrial genome research for diploid potatoes, providing a steppingstone into evolutionary studies and 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.

Adaptability, stability, and productivity of potato breeding clones and cultivars at high latitudes in Europe

The aim of potato breeding is to release cultivars that exhibit high and stable performance across the target population of environments. The objective of this research was therefore to investigate the use of various methods (site regression [SREG], coefficient of variation and regression deviation [σ2δ]) for determining the adaptability and stability of productive and quality traits in the Nordic region of Europe. The multi-environment trials included 256 breeding clones and released cultivars grown by EU farmers at three distinct testing sites over two years in Sweden. There was significant (P < 0.001) variation in tuber yield, starch percentage and reducing sugars in the tuber flesh among the breeding clones and cultivars, testing environments and the genotype by environment interaction (GEI). The environments were very diverse, as revealed by the SREG biplots and particularly for the GEI patterns noted in terms of their productive and quality characteristics. The percentage of stable high-tuber yielding germplasm was greater for breeding clones (23%) than for released European cultivars (2%), thus revealing the advantage of potato breeding in the target population of environments. SLU 1415001 and SLU 1314015 were the most promising breeding clones due to their stable high tuber yield. This characteristic was best for the starch potato cultivars, although none of them exhibited a significant different σ2δ. ‘Talent’ shows an almost stable good performance among low reducing sugar cultivars and breeding clones, which are often unstable in terms of their scoring across environments. Neither a breeding clone nor a cultivar was at the top for stable tuber yield, tuber flesh starch or reducing sugars in the tuber flesh, which shows the challenge faced by potato breeding while addressing the needs of different markets.

A Case Study on The Evaluation of Maturity Class in Potato Breeding Trials Using UAV Imagery

In potato breeding, maturity class (MC) is a crucial selection criterion because this is a critical aspect of commercial potato production. Currently, the classification of potato genotypes into MCs is done visually, which is time- and labor-consuming. The objective of this research was to use vegetation indices (VIs) derived from unmanned aerial vehicle (UAV) imagery to remotely assign MCs to potato plants grown in trials, representing three different early stages within a multi-year breeding program. The relationships between VIs (GOSAVI – Green Optimized Soil Adjusted Vegetation Index, MCARI2 – Modified Chlorophyll Absorption Index-Improved, NDRE – Normalized Difference Red Edge, NDVI – Normalized Difference Vegetation Index, and OSAVI – Optimized Soil Adjusted Vegetation Index and WDVI – Weighted Difference Vegetation Index) and visual potato canopy status were determined. Further, this study aimed to identify factors that could improve the accuracy (decrease Mean Absolute Error – MAE) of potato MC estimation remotely. Results show that VIs derived from UAV imagery can be effectively used to remotely assign MCs to potato breeding lines, with higher accuracy for the potato B-clones (20 plants per plot) than the A-clones (6 plants per plot). Among the tested VIs, the NDRE allowed for potato MC evaluation with the lowest MAE. Applying NDRE for remote MC estimation using a validation dataset of potato B-clones (100 plants per plot), resulted in an MC estimate with a 0.81 MAE. However, the accuracy of potato MC estimation using UAV image-based methods should be improved by reducing the potato canopy’s variability (increasing uniformity) within the plot. This could be achieved by minimizing 1) potato vines bending over the neighboring row, causing vine overlap between plots, and 2) plants damaged by tractor wheels during field operations.

Potential of near-infrared spectroscopy (NIRS) for prediction of acrylamide formation in French fries in the potato breeding process

Breeding goals of potatoes for deep-frying purposes include high starch contents, good suitability for long-term storage, and low tendency to form reducing sugars as acrylamide precursors. Due to the extensive number of samples, an accurate analysis of acrylamide in French fries and its precursors in tubers is difficult to implement in the breeding process. Therefore, this study aimed to evaluate the suitability of NIRS measurements after minimal sample processing for the prediction of reducing sugar contents in the tubers or acrylamide contents in French fries. An external validation with more than 650 samples consisting of 194 potato genotypes resulted in a prediction accuracy of 51 % for acrylamide and 76 % for reducing sugar content. RPD values of less than 1.5 for acrylamide and between 1.64 and 2.23 for reducing sugar prediction rendered low medium to medium model quality. Nevertheless, acrylamide prediction models based on NIRS measurement of mashed tubers categorised over 80 % of unknown samples correctly as being below or above the European threshold value, indicating suitability as rapid test procedure in the breeding process.

Test results of new breeding potato hybrids in the conditions of the Volga-Vyatka region

In the period from 2016 to 2022 in the conditions of the Kirov region, an assessment of hybrid potato combinations was carried out according to the most important traits - high productivity and yield, marketable and consumer qualities of tubers. New potato hybrids bred by the Falenki Breeding Station – branch of the FARC North-East were used as the objects of the research: 6-17 (‘Gornyak’ x ‘Manifest’); 15-17 (428-05 x ‘Manifest’); 33-17 (132-07 x ‘Manifest’); 72-17 (‘Gornyak’בIrbitsky’); 78-17 (‘Udacha’ x 428-05); 120-17 (‘Utyonok’בReggi’); 25-16 (‘Kupalinka’ x 428-05). They were noted as the most promising ones according to the results of the research of 2016-2022. The medium-early ‘Nevsky’ cultivar approved for use in the Kirov region was used as a standard. According to the methodological guidelines of the potato breeding process, phenological observations, productivity assessment (on day 65), total and commercial yields were carried out in the nursery, and the chemical composition of tubers was determined. As a result, on average, over three years of testing for a complex of economically valuable traits, a promising breeding number 33-17 was identified – a significant excess of the total yield (29.9 t/ha) over the standard ‘Nevsky‘ cultivar was 14.6 t/ha. The tubers are oval with a red, slightly reticulated skin, the eyes are small, unpainted, the flesh is white. In addition, when evaluating the productive capabilities of potato hybrids, the coefficient of adaptability of breeding number 33-17 was 1.40, which makes it possible to recommend it for cultivation in this region in order to obtain stable yields.

Molecular Insights into the Role of Sterols in Microtuber Development of Potato Solanum tuberosum L.

Potato tubers are reproductive and storage organs, enabling their survival. Unraveling the molecular mechanisms that regulate tuberization is crucial for understanding how potatorespond to environmental stress situations and for potato breeding. Previously, we did a transcriptomic analysis of potato microtuberization without light. This showed that important cellular processes like ribosomal proteins, cell cycle, carbon metabolism, oxidative stress, fatty acids, and phytosterols (PS) biosynthesis were closely connected in a protein-protein interaction (PPI) network. Research on PS function during potato tuberization has been scarce. PS plays a critical role in regulating membrane permeability and fluidity, and they are biosynthetic precursors of brassinosteroids (BRs) in plants, which are critical in regulating gene expression, cell division, differentiation, and reproductive biology. Within a PPI network, we found a module of 15 genes involved in the PS biosynthetic process. Darkness, as expected, activated the mevalonate (MVA) pathway. There was a tight interaction between three coding gene products for HMGR3, MVD2, and FPS1, and the gene products that synthetize PS, including CAS1, SMO1, BETAHSD, CPI1, CYP51, FACKEL, HYDRA1, SMT2, SMO2, STE1, and SSR1. Quantitative real-time polymerase chain reaction (qRT-PCR) confirmed the expression analysis of ten specific genes involved in the biosynthesis of PS. This manuscript discusses the potential role of genes involved in PS biosynthesis during microtuber development.

Genetic markers identify duplicates in Nordic potato collections.

The first small scale cultivation of potatoes in the Nordic countries began roughly 300 years ago, and later became an important staple food in the region. Organized conservation efforts began in the 1980s, and today, potato landraces, improved varieties, and breeding lines are conserved in genebanks at the Nordic Genetic Resource Center (NordGen), Sweden, and the Norwegian Genetic Resource Centre (NGS), Norway, as well as at potato breeding companies across Nordic countries. All these collections house a diverse array of genotypes with local names and local growing histories from the whole region. However, the presence of duplicates, and inconsistent naming has led to confusion. In this study, 198 accessions of cultivated potato (Solanum tuberosum L.) have been genotyped with 62 microsatellite (SSR) markers. The analyzed accessions came from three collections: 43 accessions from the Danish Potato Breeding Foundation in Vandel (LKF-Vandel), 90 from NordGen and 65 from NGS. The genetic analysis revealed 140 unique potato genotypes and 31 groups/clusters of duplicates, most of which contained duplicate pairs and the others three to ten accessions. Several accessions with distinct names were genetically identical or very similar, suggesting historical sharing, and regional distribution of seed potatoes, leading to the emergence of diverse local names. Moreover, many improved varieties from early potato breeding were revealed to have duplicates that have been considered Nordic landraces. Furthermore, potato accessions with identical names but originating from different collections were confirmed to be duplicates. These findings have already influenced management decisions and will further improve management practices for Nordic potato collections. Additionally, this new knowledge will benefit Nordic potato breeding efforts and allow for the dissemination of more accurate information to other users of potato diversity.

Branching response to stem density and its impact on yield in hybrid potato grown from true seeds and seedling tubers

ContextHybrid potato crops can be grown from true potato seeds or from seedling tubers. True-seed-grown plants produce lower marketable tuber yield than seedling-tuber-grown plants, because of their low early vigour and distinct growth and development patterns, notably in term of main stem number and stem branching. These differences are pivotal for yield formation but their impacts on crop performance and yield are not well understood. ObjectivesWe quantified the differences between the propagule types (true seeds vs seedling tubers) in their branching responses to stem density and assessed to what extent these differences contribute to differences in crop development and tuber production. MethodsTwo field experiments were conducted in different years, planting transplants from true seeds and pre-sprouted seedling tubers from the same genotype, while controlling their stem density per unit area. Responses in stem branching and biomass partitioning to stem density were quantified on individual main stems, followed by an evaluation of the impact of these responses on crop performance. ResultsOn individual main stems in both propagule types, higher stem density decreased branch development, decreased the number of branches above- and belowground, resulted in shifts in aboveground branch distribution towards lower branching orders, and led to smaller tuber sizes. However, such branching responses were stronger in true-seed-grown plants than in seedling-tuber-grown plants. At crop level, differences between propagule types were significant in canopy duration, number of tubers, tuber size distribution and marketable yield, but there was no stem density effect. ConclusionOur results emphasized the differences between propagule types in branching and its impact on crop development and tuber yield, due to the absence of stem density effects. Propagule type effects could be attributed to intrinsic differences between propagule types in branching control, growth habit and source-sink relations. These effects are relevant for hybrid potato breeding and require further research. Management practices were partly responsible for year-to-year differences in branching and yield formation, which highlights their significance for hybrid potato production.

Effects of different growth hormones on Solanum tuberosum L. callus induction and regeneration

This study was carried out to develop a protocol for callus induction, regeneration, shoot, and root induction in two potato cultivars (Riviera and Almonda) that can be further used to develop genetically modified plants. Callus was induced from leaf and internodal explants on Murashige and Skoog's medium (MS) supplemented with different combinations of hormones. The highest percentage of callus induction was obtained from the internodal explants of Riviera cultivar was 100% in Callus Induction Media I (CIM I) supplemented with 2 mg/L Benzyl Adenine (BA), 0.2 mg/L ?-Naphthalene Acetic Acid (NAA), 2 mg/L 2,4-Dichlorophenoxy acetic acid (2,4-D), 0.2 mg/L Kinetin (Kin) and 0.2 mg/L gibberellic acid (GA3). After one-month calli were shifted to Shoot Induction Media I and II (SIM I and SIM II), the highest percentage for shoot induction was 33.3% with the leaf explants of Riviera cultivar on SIM II supplemented with 2 mg/L BA, 0.2 mg/L NAA, 0.5 mg/L Kin and 0.2 mg/L GA3. The root induction percentage was 100% for both cultivars. Regenerated potato plants had normal leaf shapes with uniform morphology. These findings provide valuable insights for developing tissue culture protocols for potato regeneration, which are essential for genetic engineering and potato breeding programs.

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.

Transcriptome Analysis Reveals Genes and Pathways Associated with Drought Tolerance of Early Stages in Sweet Potato (Ipomoea batatas (L.) Lam.).

The yield of sweet potato [Ipomoea batatas (L.) Lam] can be easily threatened by drought stress. Typically, early stages like the seedling stage and tuber-root expansion stage are more vulnerable to drought stress. In this study, a highly drought-tolerant sweet potato cultivar "WanSu 63" was subjected to drought stress at both the seedling stage (15 days after transplanting, 15 DAT) and the tuber-root expansion stage (45 DAT). Twenty-four cDNA libraries were constructed from leaf segments and root tissues at 15 and 45 DAT for Next-Generation Sequencing. A total of 663, 063, and 218 clean reads were obtained and then aligned to the reference genome with a total mapped ratio greater than 82.73%. A sum of 7119, 8811, 5463, and 930 differentially expressed genes were identified from leaves in 15 days (L15), roots in 15 days (R15), leaves in 45 days (L45), and roots in 45 days (R45), respectively, in drought stress versus control. It was found that genes encoding heat shock proteins, sporamin, LEA protein dehydrin, ABA signaling pathway protein gene NCED1, as well as a group of receptor-like protein kinases genes were enriched in differentially expressed genes. ABA content was significantly higher in drought-treated tissues than in the control. The sweet potato biomass declined sharply to nearly one-quarter after drought stress. In conclusion, this study is the first to identify the differentially expressed drought-responsive genes and signaling pathways in the leaves and roots of sweet potato at the seedling and root expansion stages. The results provide potential resources for drought resistance breeding of sweet potato.

Generation of a Potato Radiation Mutation System to Analyse the Features of Radiation Mutant RM1

Potatoes are widely planted worldwide and are the third most important food crop. Mutation breeding involves the artificial use of various physical and chemical factors to induce plants to produce new genotypes. In this study, we established a potato radiation mutation system and analysed the features of a radiation mutant. The LD50 of the potato callus was 24.8 Gy after linear regression analysis. The radiation mutant 1 (RM1) showed significant dwarfism and strong growth; RM1 plants decreased in height by 31%. The root and leaf fresh weights of the RM1 increased 1.8-fold compared to the wild-type (WT, Chuanyu 10) cultivar. Leaf microstructure results showed that the thicknesses of the upper epidermis and lower epidermis of RM1 plants were greater than those of the WT cultivar. Transcriptome analysis of seeding revealed 1179 upregulated and 1641 downregulated differentially expressed genes (DEGs) in RM1 plants. Further analysis showed that the expression levels of WRKY and MYB transcription factors, CIPK and MAPK protein kinases, ABC transporters, hormones, and ROS pathway genes were altered. These results provide theoretical support for potato breeding research and enrich the functional network of vital breeding-related genes.

Heterologous expression of distinct insecticidal genes in potato cultivars encodes resistance against potato tuber moth, Phthorimaea operculella (Zeller) (Lepidoptera: Gelechiidae)

AbstractThe potato tuber moth, Phthorimaea operculella (Zeller), is a notorious insect pest of potato incurring substantial yield losses in the field as well as in storage. Chemical control is difficult to exercise due to the latent feeding of the caterpillars and their ability to develop resistance against insecticides. One of the essential components of efficient insect-resistant management is using two or more different insecticidal genes in transgenic crops to effectively avoid and delay the resistance development in insect pests. Two constructs, namely DS-1 (cry3A + SN-19 genes) and DS-2 (OCII + SN-19 genes) in pCAMBIA1301 binary vector, were developed and were transformed in potato cultivars (Agria and Lady Olympia) via Agrobacterium-mediated transformation. The molecular analysis confirmed gene integration and expression of the introduced genes in transgenic plants. The insecticidal effects of incorporated genes in transgenic plants were assessed against 1st, 2nd, 3rd, and 4th instar potato tuber moth (PTM) larvae. The transgenic plants endured significantly high mortalities (100%) of larval stages of PTM within 72 h. Our results show that these transgenic potato plants have the potential to control populations of PTM and are also useful tools in managing PTM that would ultimately reduce the dependency on conventional chemical pesticides with potentially less or minimal hazards. These lines can also serve as an excellent source of germplasm for potato breeding program.

Cytokinin Oxidase (CKX) Family Members in Potato (Solanum tuberosum): Genome-Wide Identification and Expression Patterns at Seedling Stage under Stress

Cytokinin (CK) is an important hormone that regulates cell differentiation. The CK content in plants is regulated by cytokinin oxidase (CKX), an important enzyme that participates in hormone-regulated pathways. Additionally, CKXs comprise a large family of enzymes, but little information exists on the CKXs in potato (Solanum tuberosum). In this study, nine CKXs were identified in the potato genome and named StCKX01-09, according to their order on the linkage groups (LGs). They belong to six subfamilies, and the members within the respective subfamilies had similar motifs, a similar gene structure, and similar cis-acting elements. Additionally, the CKXs from four other species, including Arabidopsis, rice (Oryza sativa), soybean (Glycine max), and maize (Zea mays), were also divided into six subfamilies, while members within each subfamily had similar types of motifs. Moreover, the potato StCKXs were shown to influence plant hormones and stress-related factors. StCKXs were collinear, with one CKX in Arabidopsis and five CKXs in Glycine max. Quantitative real-time PCR (qRT-PCR) revealed tissue-specific expression patterns in the potato seedlings and changes in the expression levels in response to stress. Furthermore, the cytokinin content and CKX enzyme activity were shown to be regulated by StCKXs. This study provides detailed information that can help future endeavors in the molecular breeding of potato (Solanum tuberosum).