Dune Russet (COTX08063-2Ru) is the first French fry russet potato cultivar released by the Texas A M Potato Breeding Program. It derives from a cross made by the Colorado State University Potato Program between Premier Russet and A99073-1 and was subsequently selected and advanced by the Texas Program. Dune Russet has oblong potato tubers with light russet skin texture and white flesh. It is characterized by having excellent French fry quality and cold-induced sweetening resistance, producing light-colored fries directly from the field and even after several months (three to eight) in cold storage at 4.4 °C. Dune Russet is especially recommended for areas that experience high-temperature stress during the growing season, as it can retain high specific gravity near 1.090 and produce light French fries despite heat stress. Across multi-location trials, Dune Russet outperformed the reference cultivar, Russet Burbank, and other processing cultivars in French fry quality, while offering some field-based PVY tolerance and good agronomic performance, including competitive marketable yields and a high proportion of US No. 1 tubers.

Upon harvest, potato (Solanum tuberosum L.) tubers enter a dormant state and do not sprout even under favorable conditions. Early dormancy break causes tuber spoilage and reduces postharvest quality. Common sprout control methods may compromise tuber quality, raise health and environmental concerns, and increase costs. Thus, potato varieties with long tuber dormancy are desirable to reduce tuber spoilage and lower costs for sprout prevention. This study aimed to (i) explore phenotypic variation in tuber dormancy length among advanced tetraploid potato genotypes and several public cultivars, (ii) understand the genetic basis of tuber dormancy, and (iii) obtain genomic-estimated breeding values (GEBVs) using genomic selection. A panel of 216 tetraploid potato genotypes, mostly from the Texas A&M Potato Breeding Program, was grown in Springlake and Dalhart, TX, from 2019 to 2021, for tuber dormancy evaluation. An additional panel of 82 genotypes was evaluated in 2022. A wide range of tuber dormancy lengths was observed, and significant variations were found among genotypes, field locations, storage conditions, and market groups. Quantitative trait loci were detected on chromosomes 1, 2, 3, 5, 6, 9, and 11, each explaining up to 11.8% of phenotypic variation. In addition, GEBVs were obtained using StageWise. Potato genotypes with high GEBVs for tuber dormancy length are potential donors of genes that can extend the dormancy period. Variation in tuber dormancy among advanced tetraploid potato genotypes highlighted the potential for selection. The genomic regions identified and the GEBVs provided valuable insights into the genetic basis of potato tuber dormancy, offering guidance for breeding.

Vanguard Russet, a fresh market potato developed by the Texas A M Breeding Program, has been reported to be heat tolerant based on previous greenhouse and field studies. Until now, no studies have been conducted to understand the mechanisms involved in its heat tolerance. We compared Vanguard Russet and the heat-sensitive potato variety Russet Burbank using contrasting conditions in growth chambers (normal, 25/15⁰C day/night vs. high-temperature, 25/15⁰C day/night for four weeks, followed by 35/25⁰C day/night). Differences in tuber initiation time, bulking, tuber number, plant height, leaf area, stem thickness, leaf angle, plant biomass, and photosynthetic parameters were sequentially documented at five-time points: 30, 45, 60, 75, and 100 days after planting. Although having slower above-ground plant growth under both conditions, Vanguard Russet initiated tuber formation significantly earlier (< 30 days) than Russet Burbank (30–45 days). This indicates its ability to quickly channel photoassimilates toward tubers, employing early tuberization as a possible heat escape strategy. Screening for early tuberization could be considered as an initial approach to identify varieties able to escape heat stress. In addition to early tuberization, heat-tolerant varieties must produce a high yield of marketable tubers with few internal and external defects.

Heat stress during the potato growing season reduces tuber marketable yield and quality. Tuber quality deterioration includes external (heat sprouts, chained tubers, knobs) and internal (vascular discoloration, hollow heart, internal heat necrosis) tuber defects, as well as a reduction in their specific gravity and increases in reducing sugars that result in suboptimal (darker) processed products (french fries and chips). Successfully cultivating potatoes under heat-stress conditions requires planting heat-tolerant varieties that can produce high yields of marketable tubers, few external and internal tuber defects, high specific gravity, and low reducing sugars (in the case of processing potatoes). Heat tolerance is a complex trait, and understanding its genetic basis will aid in developing heat-tolerant potato varieties. A panel of 217 diverse potato clones was evaluated for yield and quality attributes in Dalhart (2019 and 2020) and Springlake (2020 and 2021), Texas, and genotyped with the Infinium 22 K V3 Potato Array. A genome-wide association study was performed to identify genomic regions associated with heat-tolerance traits using the GWASpoly package. Quantitative trait loci were identified on chromosomes 1, 3, 4, 6, 8, and 11 for external defects and on chromosomes 1, 2, 3, 10, and 11 for internal defects. Yield-related quantitative trait loci were detected on chromosomes 1, 6, and 10 pertaining to the average tuber weight and tuber number per plant. Genomic-estimated breeding values were calculated using the StageWise package. Clones with low genomic-estimated breeding values for tuber defects were identified as donors of good traits to improve heat tolerance. The identified genomic regions associated with heat-tolerance attributes and the genomic-estimated breeding values will be helpful to develop new potato cultivars with enhanced heat tolerance in potatoes.

In potato breeding, morphological tuber traits are important selection targets to meet the demands of the fresh and processing markets. Understanding the genetic basis of tuber traits should guide selection and improve breeding efficiencies. However, this is challenging in potato due to the complexity of the traits and the polyploid nature of the potato genome. High-throughput affordable molecular markers and new software specific for polyploid species have the potential to unlock previously unattainable levels of understanding of the genetic basis of tuber traits in tetraploid potato. In this study, we genotyped a diversity panel of 214 advanced clones with the 22 K SNP potato array and phenotyped it in three field environments in Texas. We conducted a genome-wide association study using the GWASpoly software package to identify genomic regions associated with tuber morphological traits. Some of the QTLs discovered confirmed prior studies, whereas others were discovered for the first time. The main QTL for tuber shape was detected on chromosome 10 and explained 5.8% of the phenotypic variance. GWAS analysis of eye depth detected a significant QTL on chromosome 10 and explained 3.9% of the phenotypic variance. Another QTL peak for eye depth on chromosome 5 was located near the CDF1 gene, an important regulator of maturity in potato. Our study found that multiple QTLs govern russeting in potato. A major QTL for flesh color on chromosome 3 that explained 26% of the phenotypic variance likely represents the Y locus responsible for yellow flesh in potato tubers. Several QTLs were detected for purple skin color on chromosome 11. Furthermore, genomic estimated breeding values were obtained, which will aid in the early identification of superior parental clones that should increase the chances of producing progenies with higher frequencies of the desired tuber traits. These findings will contribute to a better understanding of the genetic basis of morphological traits in potato, as well as to identifying parents with the best breeding values to improve selection efficiency in our potato breeding program.

In recent years, heat stress has affected potato production more frequently, resulting in lower marketable yields and reduced tuber quality. In order to develop heat-tolerant potatoes, it is necessary to select under heat-stress conditions and consider traits affected by heat stress. The Texas A&M Potato Breeding Program has selected potatoes under high-temperature stress for several decades. Ten potato cultivars, representing heat tolerant and sensitive clones based on past performance in Texas, were included in field trials for three years at the two main locations used by the Texas Breeding Program (Dalhart and Springlake, TX) to assess if the Texas field locations are suitable for heat tolerance screening. Both locations were confirmed as appropriate for heat stress screening. However, Springlake was a more stressful location since it had significantly lower yields of marketable tubers and increased percentages of tuber defects. Planting time did not have a significant effect at the most stressful location. The same ten potato clones were included in greenhouse experiments with contrasting temperatures (normal versus heat stress). There was confirmation that heat stress conditions resulted in significantly lower marketable yields, specific gravity, dormancy, and significantly higher percentages of tuber defects; however, significant differences existed between potato clones. Under heat stress conditions, Russet Burbank had a high percent of tubers with external defects, whereas Atlantic showed the highest percentage of internal defects (mainly internal heat necrosis). Vanguard Russet produced the highest marketable yield while maintaining a low percentage of external and internal defects. Russet Burbank and Atlantic were heat-sensitive controls for external and internal tuber defects, respectively. In contrast, Vanguard Russet can be used as a reliable heat-tolerant control. Including appropriate controls in heat stress studies will help identify clones with heat tolerance.

Malnutrition is a major public health concern in many parts of the world. Among other nutrients, minerals are necessary in the human diet. Potato tubers are a good source of minerals; they contribute 18% of the recommended dietary allowance of potassium; 6% of copper, phosphorus, and magnesium; and 2% of calcium and zinc. Increased public interest in improving the nutritional value of foods has prompted the evaluation of mineral content in tubers of advanced genotypes from the Texas A&M Potato Breeding Program and the investigation of the genetics underlying mineral composition in tubers. The objectives of this study were to i) assess phenotypic variation for mineral content in tubers of advanced potato genotypes, ii) identify genomic regions associated with tuber mineral content, and iii) obtain genomic-estimated breeding values. A panel of 214 advanced potato genotypes and reference varieties was phenotyped in three field environments in Texas for the content of 12 minerals in tubers and genotyped using the Infinium Illumina 22K V3 single nucleotide polymorphism (SNP) Array. There was significant variation between potato genotypes for all minerals evaluated except iron. As a market group, red-skinned potatoes had the highest amount of minerals, whereas russets had the lowest mineral content. Reds had significantly higher P, K, S, and Zn than russets and significantly higher P and Mg than chippers. Russets had significantly higher Ca, Mg, and Na than chippers. However, the chippers had significantly higher K than the russets. A genome-wide association study for mineral content using GWASpoly identified three quantitative trait loci (QTL) associated with potassium and manganese content on chromosome 5 and two QTL associated with zinc content on chromosome 7. The loci identified will contribute to a better understanding of the genetic basis of mineral content in potatoes. Genomic-estimated breeding values for mineral macro and micronutrients in tubers obtained with StageWise will guide the selection of parents and the advancement of genotypes in the breeding program to increase mineral content in potato tubers.

Potato is the most consumed vegetable worldwide. Potato tubers contain water, starch, proteins, minerals, and vitamins. The amounts of these chemicals depend on the cultivar and growing location. When potatoes are exposed to high temperatures during the growing period, tuber yield and quality are detrimentally affected; however, there is limited knowledge about the influence of high temperatures on tuber chemical composition. With temperatures rising around the globe, the reaction of potato cultivars to high temperatures is increasingly important, and heat-induced changes, including changes in the chemical composition of tubers, should be considered. The Texas A&M University Potato Breeding Program has been selecting potato clones under high-temperature conditions for many years. Several released cultivars are considered heat-tolerant based on high marketable yields and low internal and external tuber defects. In this study, we used Raman spectroscopy (RS), an analytical tool, to determine whether heat stress causes changes in the chemical composition of tubers of ten potato cultivars. RS is a non-invasive method that requires less time and labor than conventional chemical analysis. We found drastic changes in the intensities of vibrational bands that originate from carbohydrates in the spectra acquired from tubers of heat-stressed plants compared to tubers produced by potato plants grown under normal conditions. These results demonstrate that RS could be used as a replacement or complement to conventional chemical analysis to inspect the effect of heat stress on tuber chemical composition.

Free amino acids in potato tubers contribute to their nutritional value and processing quality. Exploring the natural variation in their accumulation in tubers across diverse genetic backgrounds is critical to potato breeding programs aiming to enhance or partition their distribution effectively. This study assessed variation in the tuber-bound free amino acids in a diversity panel of tetraploid potato clones developed and maintained by the Texas A&M Potato Breeding Program to explore their genetic basis and to obtain genomic-estimated breeding values for applied breeding purposes. Free amino acids content was evaluated in tubers of 217 tetraploid potato clones collected from Dalhart, Texas in 2019 and 2020, and Springlake, Texas in 2020. Most tuber amino acids were not affected by growing location, except histidine and proline, which were significantly lower (− 59.0%) and higher (+ 129.0%), respectively, at Springlake, Texas (a location that regularly suffers from abiotic stresses, mainly high-temperature stress). Single nucleotide polymorphism markers were used for genome-wide association studies and genomic selection of clones based on amino acid content. Most amino acids showed significant variations among potato clones and moderate to high heritabilities. Principal component analysis separated fresh from processing potato market classes based on amino acids distribution patterns. Genome-wide association studies discovered 33 QTL associated with 13 free amino acids. Genomic-estimated breeding values were calculated and are recommended for practical potato breeding applications to select parents and advance clones with the desired free amino acid content.

Potato is a major food crop in the United States and around the world. Most potatoes grown in the United States are destined for processing. Genomic selection can speed up breeding progress for important traits, including those with complex inheritance by guiding the identification of the best parents and guiding selection to advance clones in the breeding program. However, the application of genomic selection in polyploid species has been challenging. In this study, we obtained breeding values of 384 chipping clones evaluated in Texas between 2017 and 2020. The mean reliability of the genomic-estimated breeding values obtained were 0.77, 0.41, 0.61, 0.71, and 0.24 for chip color, chip quality, specific gravity, vine maturity, and total yield, respectively. Potato clones with good chip quality, high yield, high specific gravity, and light-color chips were identified using a multi-trait selection index based on weighted standardized genomic-estimated breeding values. Genome-wide association studies identified quantitative trait loci on chromosome 5 for vine maturity and chromosomes 1, 3, and 7 for chip color. This research has laid the groundwork for implementing genomic selection in tetraploid potato breeding and understanding the genetic basis of chip processing traits in potatoes.

Vanguard Russet (TX08352-5Ru) is a medium-early maturing potato cultivar released by Texas A&M AgriLife Research in 2018. Vanguard Russet produces attractive oblong to long tubers with medium russet skin and white flesh, blocky shape and uniform size, ideally suited for the fresh market. Vanguard Russet produces. It produces a high yield of marketable tubers, with many tubers in the 170 to 510 g size category, some oversized (> 510 g) tubers, and fewer culls than Russet Norkotah. Vanguard Russet has low external tuber defects (growth cracks, second growth), internal tuber defects (hollow heart, internal brown spot, vascular discoloration, blackspot bruise), and has a long tuber dormancy. Vanguard Russet is susceptible to PVY but has good symptom expression and is moderately resistant to common scab and Fusarium dry rot. Vanguard Russet is an excellent cultivar option for fresh market potato production due to its high marketable yields, excellent external and internal tuber quality, and long tuber dormancy.

Potato (Solanum tuberosum L.) is a staple food crop and part of an industry valued at an estimated $3.77 billion in the United States. Many varieties of potato are susceptible to zebra chip disease (ZC), a psyllid-vectored bacterial infection that renders the tubers unmarketable due to unappealing discoloration and taste. Similarly, potato virus Y (PVY) is a major pathogen of potatoes and other solanaceous crops that causes devastating damage to both foliage and tubers. These diseases are typically detected by enzyme-linked immunosorbent assay or polymerase chain reaction. ZC can also be diagnosed by a visual inspection of cut open tubers followed by frying to reveal the characteristic striping symptoms. However, these methods are invasive and destructive, as well as reagent, time, and labor consuming. Thus, quick and sample-general alternative methods for disease detection are highly desirable. In this proof-of-principle work, we demonstrate that spatially offset Raman spectroscopy (SORS) shows great potential for rapid and reagent-free detection of ZC or PVY diseases. Such detection is based on Raman identification of chemical changes in tubers associated with ZC or PVY. Chemometric analysis of spectra from intact potato tubers demonstrated over 90% accuracy of ZC detection. With data from cut open tubers, the prediction accuracy for ZC increased to over 90% for the prediction of PVY disease. We also show that potatoes from plants with either ZC or PVY diseases can be distinguished from each other and healthy tubers with approximately 95% accuracy. These results suggest that SORS has potential for noninvasive diagnostics of potato diseases.

Knowledge regarding genetic diversity and population structure of breeding materials is essential for crop improvement. The Texas A&M University Potato Breeding Program has a collection of advanced clones selected and maintained in-vitro over a 40-year period. Little is known about its genetic makeup and usefulness for the current breeding program. In this study, 214 potato clones were genotyped with the Infinium Illumina 22 K V3 Potato Array. After filtering, a total of 10,106 single nucleotide polymorphic (SNP) markers were used for analysis. Heterozygosity varied by SNP, with an overall average of 0.59. Three groups of tetraploid clones primarily based on potato market classes, were detected using STRUCTURE software and confirmed by discriminant analysis of principal components. The highest coefficient of differentiation observed between the groups was 0.14. Signatures of selection were uncovered in genes controlling potato flesh and skin color, length of plant cycle and tuberization, and carbohydrate metabolism. A core set of 43 clones was obtained using Core Hunter 3 to develop a sub-collection that retains similar genetic diversity as the whole population, minimize redundancies, and facilitates long-term conservation of genetic resources. The comprehensive molecular characterization of our breeding clone bank collection contributes to understanding the genetic diversity of existing potato resources. This analysis could be applied to other breeding programs and assist in the selection of parents, fingerprinting, protection, and management of the breeding collections.

The study was carried out at Texas A&M University Potato Breeding and Variety Program in 2015, and the same study was repeated for the second time in 2016 for the reliability of the results. The five potato viruses chosen were PVX, PVY, PVS, PVM and PLRV because of their ease of inoculation by mechanical transmission. Five virus positive potato selections, virus that were obtained from the Texas A&M University Potato Breeding and Variety Program and Colorado State University Program, were used in this study. Control (tissue culture alone), chemotherapy, thermotherapy and combinations of chemotherapy+thermotherapy were used to eradicate the viruses. The control (tissue culture alone) application did not give successful results in virus eradication. Chemotherapy showed the greatest success in clearing PVM (75%-66.667%) in both years. Thermotherapy application showed the highest success in eradication of PLRV with 58.30% in the first year and 75.00% in the second year. Combining thermotherapy and chemotherapy was effective in eliminating both PVY and PLRV.

Long-term maintenance in vitro of potato plantlets in nutrient media is necessary to preserve disease-free stocks. Since these are living plants, they eventually outgrow the containers they are in and exhaust the media, so propagation onto fresh media is required. To decrease labor and time spent in this process, it is of interest to slow plant growth to reduce turnover frequency. In this study, we investigated the effects of adding two concentrations (2 and 4%) of mannitol (a sugar alcohol that causes osmotic stress) to tissue culture media on plant growth of three potato clones at moderately low temperatures. Plantlet growth was inversely proportional to the concentration of mannitol used, but there were genotypic differences. Regeneration of the plantlets for subsequent micropropagation, after removal from the main treatments at day 64 and 121 days, was not negatively affected by the percentage of mannitol used to maintain the original stocks. Based on these results, we started using 2% mannitol as a baseline for practical long-term storage of potato breeding clones maintained in vitro. Depending on the reaction of the specific genotypes to media containing mannitol, additional adjustments might be needed.

High starch content, simplicity of cultivation, and high productivity make potatoes (Solanum tuberosum) a staple in the diet of people around the world. On average, potatoes are composed of 83% water and 12% carbohydrates, and the remaining 4% includes proteins, vitamins, and other trace elements. These proportions vary depending on the type of potato and location where they were cultivated. At the same time, the chemical composition determines the nutritional value of potato tubers and can be proved using various wet chemistry and spectroscopic methods. For instance, gravity measurements, as well as several different colorimetric assays, can be used to investigate the starch content. However, these approaches are indirect, often destructive, and time- and labor-consuming. This study reports on the use of Raman spectroscopy (RS) for completely non-invasive and non-destructive assessment of nutrient content of potato tubers. We also show that RS can be used to identify nine different potato varieties, as well as determine the origin of their cultivation. The portable nature of Raman-based identification of potato offers the possibility to perform such analysis directly upon potato harvesting to enable quick quality evaluation.

Zebra chip (ZC) disease caused by the bacterium ‘Candidatus Liberibacter solanacearum’ (Lso) and vectored by the potato psyllid (Bactericera cockerelli Šulc.) inflicts significant yield and quality losses in potato. Potato plants infected with Lso produce tubers with an internal brown stripe pattern that is unacceptable to the potato processing industry. Potato varieties tolerant of ZC disease could reduce yield and quality losses caused by the disease, as well as diminish insecticide usage to control potato psyllids. Tetraploid potato clones selected from breeding programs in the US were screened in Texas under both greenhouse and field conditions. Chipping quality in tubers harvested from plants infested with Lso-infected psyllids and those harvested from from non-infested plants were compared, and tuber symptoms associated with ZC disease were evaluated. Clones showing good chipping quality and promising ZC tolerance in the greenhouse and first field trials were independently tested in a second field trial. Clones of the A07781 and TX12484 families consistently showed good processing quality and ZC tolerance over multiple evaluations. These findings indicate that good processing clones with tolerance to ZC disease are available. These clones could be used by potato breeding programs as parents and could also be used to study the genetics of tolerance to ZC disease.

‘Candidatus Liberibacter solanacearum’ (Lso) is a phloem-restricted plant pathogen that is vectored between host plants by the potato psyllid, Bactericera cockerelli. Lso infects solanaceous crops whithin North America and New Zealand and is responsible for causing zebra chip (ZC) in potato. Two Lso haplotypes (A and B) have been identified infecting potato (Solanum tuberosum). Previously, we identified differences in disease severity associated with each Lso haplotype in tomato (Solanum lycopersicum). In this study, the severity of ZC symptoms was evaluated for Lso haplotypes A and B independently or in co-infection in Atlantic variety potato tubers grown in Texas fields. Discolorations in tuber vascular tissues were measured in potato chips using a published 6-point visual scale and compared among plants submitted to five treatments: no psyllids (control), psyllids not infected with Lso (LsoFree), psyllids infected with Lso haplotype A (LsoA), psyllids infected with Lso haplotype B (LsoB), and psyllids infected with both haplotypes (LsoAB). These experiments were performed a total of three times, twice in the Lower Rio Grande Valley (Weslaco, TX) during the winters 2014 and 2018 and once during the spring 2015 in the Texas Panhandle (Springlake, TX). This study showed that significantly lower ZC symptom severity was associated with plants treated with LsoA-infected psyllids compared to plants treated with either LsoB- or LsoAB-infected psyllids; however, this difference was marginal. This difference might be relevant for the disease biology; it has no impact on the tuber suitability for the market. This study also showed that average tuber mass was significantly lower in plants infected with Lso compared with uninfected plants and that this reduction in mass was similar among Lso haplotype treatments. Overall, this study demonstrates that Lso haplotypes A and B cause slightly different ZC symptom severity and that ZC symptom severity in plants treated with psyllids co-infected with both haplotypes is similar to the symptoms associated with Lso haplotype B.