39 research outputs found
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Expression Levels of the γ-Glutamyl Hydrolase I Gene Predict Vitamin B9 Content in Potato Tubers
Biofortification of folates in staple crops is an important strategy to help eradicate human folate deficiencies. Folate biofortification using genetic engineering has shown great success in rice grain, tomato fruit, lettuce, and potato tuber. However, consumers’ skepticism, juridical hurdles, and lack of economic model have prevented the widespread adoption of nutritionally-enhanced genetically-engineered (GE) food crops. Meanwhile, little effort has been made to biofortify food crops with folate by breeding. Previously we reported >10-fold variation in folate content in potato genotypes. To facilitate breeding for enhanced folate content, we attempted to identify genes that control folate content in potato tuber. For this, we analyzed the expression of folate biosynthesis and salvage genes in low- and high-folate potato genotypes. First, RNA-Seq analysis showed that, amongst all folate biosynthesis and salvage genes analyzed, only one gene, which encodes γ-glutamyl hydrolase 1 (GGH1), was consistently expressed at higher levels in high- compared to low-folate segregants of a Solanum boliviense Dunal accession. Second, quantitative PCR showed that GGH1 transcript levels were higher in high- compared to low-folate segregants for seven out of eight pairs of folate segregants analyzed. These results suggest that GGH1 gene expression is an indicator of folate content in potato tubers
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Maximizing the Nutritional Potential of Potato: the Case of Folate
Micronutrient malnutrition, also known as the hidden hunger, affects over two billion people worldwide. Potato is the third most consumed food crop in the world, and is therefore a fundamental element of food security for millions of people. Increasing the amount of micronutrients in potatoes could help alleviate worldwide micronutrient malnutrition. Folate (or vitamin B9) is an essential micronutrient in the human diet. Deficiencies in folate lead to serious, sometimes lethal, diseases. Unfortunately, folate intake remains suboptimal in both developing and developed regions of the world. This paper uses folate to illustrate various approaches that could be implemented to increase micronutrient content in potato. It provides a brief overview of recent analyses of folate content in diverse potato germplasm, of changes in folate content during tuber development, and of the effect of postharvest low temperature storage of potato on folate content, and how an optimization of these different factors could lead to significant increases in folate intake from potato
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Thiamin biofortification of crops
Thiamin is essential for human health. While plants are the ultimate source of thiamin in most human diets, staple foods like white rice have low thiamin content. Therefore, populations whose diets are mainly based on low-thiamin staple crops suffer from thiamin deficiency. Biofortification of rice grain by engineering the thiamin biosynthesis pathway has recently been attempted, with up to fivefold increase in thiamin content in unpolished seeds. However, polished seeds that retain only the starchy endosperm had similar thiamin content than that of non-engineered plants. Various factors such as limited supply of precursors, limited activity of thiamin biosynthetic enzymes, dependence on maternal tissues to supply thiamin, or lack of thiamin stabilizing proteins may have hindered thiamin increase in the endosperm
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Genetic diversity of thiamine and folate in primitive cultivated and wild potato (Solanum) species
Biofortification of staple crops like potato via breeding is an attractive strategy to reduce human micronutrient deficiencies. A prerequisite is metabolic phenotyping of genetically diverse material which can potentially be used as parents in breeding programs. Thus, the natural genetic diversity of thiamine and folate contents was investigated in indigenous cultivated potatoes (Solanum tuberosum group Andigenum) and wild potato species (Solanum section Petota). Significant differences were found among clones and species. For about 50% of the clones there were variations in thiamine and folate contents between years. Genotypes which contained over two-fold the thiamine and four-fold the folate content compared to the modern variety Russet Burbank were identified and should be useful material to integrate in breeding programs which aim to enhance the nutritional value of potato. Primitive cultivars and wild species with widely different amounts of thiamine and folate will also be valuable tools to explore their respective metabolic regulation
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Vitamin B1 content in potato: effect of genotype, tuber enlargement, and storage, and estimation of stability and broad-sense heritability
Thiamine pyrophosphate (vitamin B1) is an essential nutrient in the human diet, and is often referred as the energy vitamin. Potato contains modest amounts of thiamine. However, the genetic variation of thiamine concentrations in potato has never been investigated. In this study, we determined thiamine concentrations in freshly-harvested unpeeled tubers of fifty-four potato clones, the majority of them originating from the Pacific Northwest Potato Development Program. Tubers from thirty-nine clones were collected from four different environmental conditions. Thiamine concentrations ranged from 292 to 1317 ng g-1 fresh weight, which gives a good estimate of the genetic variation available in Solanum tuberosum ssp. tuberosum. Thirteen clones/varieties contained >685 ng g-1 fresh weight and four had >800 ng g-1 fresh weight over multiple harvests, indicating that these genotypes would contribute a significant amount of thiamine in the diet (>10% of the Recommended Daily Allowance based on a 175- or 150-g serving, respectively). Broad-sense heritability for thiamine content was calculated as 0.49 with a 95% confidence interval of 0.21–0.72, suggesting that genetic variation accounted for about 50% of the observed variation. There were significant clone and clone x environment effects. After accounting for environmental variation, 25 clones were unstable across environments. Tubers harvested at a mature stage late in the growing season had higher amounts of thiamine than tubers harvested at a young stage early in the season. Storage at cold temperature did not lead to significant thiamine loss; instead, thiamine concentrations slightly increased during storage in some genotypes. These results suggest that increasing the concentration of thiamine in potato is feasible and that all potato varieties may one day be a significant source of thiamine in the human diet
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Priming potato with thiamin to control potato virus Y
Potato virus Y (PVY) is a major potato pathogen affecting potato yields worldwide. Thiamin, a water-soluble B vitamin (vitamin B1) has been shown to boost the plant’s immunity, thereby increasing resistance against pathogens. In this study, we tested different concentrations of thiamin (1 mM, 10 mM, 50 mM, 100 mM) and multiple thiamin applications (once, biweekly and monthly,) on potato resistance to PVY in Ranger Russet potatoes. Plants were mechanically inoculated with PVYN:O. This PVY strain is known for causing well-defined foliar symptoms. We collected leaflets weekly through April and May 2014 and tested them with an enzyme-linked immunosorbent assay specific to PVY as well as by real time quantitative RT-PCR. These assays allowed us to determine the presence and level of PVY in different parts of the plants. We found that the highest thiamin concentration treatment (100 mM) produced the lowest virus level in potatoes across all dates and leaflet samples. Also, it was found that multiple applications of thiamin had a positive effect on reducing virus level, especially when thiamin was applied every four weeks
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Exploring Folate Diversity in Wild and Primitive Potatoes for Modern Crop Improvement
Malnutrition is one of the world’s largest health concerns. Folate (also known as vitamin B₉) is essential in the human diet, and without adequate folate intake, several serious health concerns, such as congenital birth defects and an increased risk of stroke and heart disease, can occur. Most people’s folate intake remains sub-optimal, even in countries that have a folic acid food fortification program in place. Staple crops, such as potatoes, represent an appropriate organism for biofortification through traditional breeding based on their worldwide consumption and the fact that modern cultivars only contain about 6% of the daily recommended intake of folate. To start breeding potatoes with enhanced folate content, high folate potato material must be identified. In this study, 250 individual plants from 77 accessions and 10 Solanum species were screened for their folate content using a tri-enzyme extraction and microbial assay. There was a 10-fold range of folate concentrations among individuals. Certain individuals within the species Solanum tuberosum subsp. andigenum, Solanum vernei and Solanum boliviense have the potential to produce more than double the folate concentrations of commercial cultivars, such as Russet Burbank. Our results show that tapping into the genetic diversity of potato is a promising approach to increase the folate content of this important crop.This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by MDPI. The published article can be found at: http://www.mdpi.com/journal/genesKeywords: andigenum, biofortification, folate, vitamin B₉, vernei, potato, Solanum tuberosu
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Single nucleotide polymorphism (SNP) markers associated with high folate content in wild potato species
Micronutrient deficiency, also known as the hidden hunger, affects over two billion people worldwide. Potato is the third most consumed food crops in the world, and is therefore a fundamental element of food security for millions of people. Increasing the amount of micronutrients in food crop could help alleviate worldwide micronutrient malnutrition. In the present study, we report on the identification of single nucleotide polymorphism (SNP) markers associated with folate, an essential micronutrient in the human diet. A high folate diploid clone Fol 1.6 from the wild potato relative Solanum boliviense (PI 597736) was crossed with a low/medium folate diploid S. tuberosum clone USW4self#3. The resulting F1 progeny was intermated to generate an F2 population, and tubers from 94 F2 individuals were harvested for folate analysis and SNP genotyping using a SolCap 12K Potato SNP array. Folate content in the progeny ranged from 304 to 2,952 ng g-1 dry weight. 6,759 high quality SNPs containing 4,174 (62%) polymorphic and 2,585 (38%) monomorphic SNPs were used to investigate marker-trait association. Association analysis was performed using two different approaches: survey SNP-trait association (SSTA) and SNP-trait association (STA). A total of 497 significant SNPs were identified, 489 by SSTA analysis and 43 by STA analysis. Markers identified by SSTA were located on all twelve chromosomes while those identified by STA were confined to chromosomes 2, 4, and 6. Eighteen of the significant SNPs were located within or in close proximity to folate metabolism-related genes. Forty two SNPs were identical between SSTA and STA analyses. These SNPs have potential to be used in marker-assisted selection for breeding high folate potato varieties
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RNA-Seq analysis of resistant and susceptible potato varieties during the early stages of potato virus Y infection
Background: Potato virus Y (PVY) is one of the most important plant viruses affecting potato production. The
interactions between potato and PVY are complex and the outcome of the interactions depends on the potato
genotype, the PVY strain, and the environmental conditions. A potato cultivar can induce resistance to a specific
PVY strain, yet be susceptible to another. How a single potato cultivar responds to PVY in both compatible and
incompatible interactions is not clear.
Results: In this study, we used RNA-sequencing (RNA-Seq) to investigate and compare the transcriptional changes
in leaves of potato upon inoculation with PVY. We used two potato varieties: Premier Russet, which is resistant to
the PVY strain O (PVYᴼ) but susceptible to the strain NTN (PVYᴺᵀᴺ), and Russet Burbank, which is susceptible to all
PVY strains that have been tested. Leaves were inoculated with PVYᴼ or PVYᴺᵀᴺ, and samples were collected 4 and
10 h post inoculation (hpi). A larger number of differentially expressed (DE) genes were found in the compatible
reactions compared to the incompatible reaction. For all treatments, the majority of DE genes were down-regulated
at 4 hpi and up-regulated at 10 hpi. Gene Ontology enrichment analysis showed enrichment of the biological
process GO term “Photosynthesis, light harvesting” specifically in PVYᴼ-inoculated Premier Russet leaves, while
the GO term “nucleosome assembly” was largely overrepresented in PVYᴺᵀᴺ-inoculated Premier Russet leaves and
PVYᴼ-inoculated Russet Burbank leaves but not in PVYᴼ-inoculated Premier Russet leaves. Fewer genes were DE
over 4-fold in the incompatible reaction compared to the compatible reactions. Amongst these, five genes were
DE only in PVYᴼ-inoculated Premier Russet leaves, and all five were down-regulated. These genes are predicted to
encode for a putative ABC transporter, a MYC2 transcription factor, a VQ-motif containing protein, a non-specific
lipid-transfer protein, and a xyloglucan endotransglucosylase-hydroxylase.
Conclusions: Our results show that the incompatible and compatible reactions in Premier Russet shared more
similarities, in particular during the initial response, than the compatible reactions in the two different hosts. Our
results identify potential key processes and genes that determine the fate of the reaction, compatible or
incompatible, between PVY and its host
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A cross-kingdom Nudix enzyme that pre-empts damage in thiamin metabolism
Genes specifying the thiamin monophos¬phate phosphatase and adenylated thiazole diphosphatase steps in fungal and plant thiamin biosynthesis remain unknown, as do genes for thia¬min diphosphate (ThDP) hydrolysis in thiamin metabolism. A distinctive Nudix domain fused to thia¬min di¬phos¬phokin¬ase (Tnr3) in Schizo¬sacc¬¬h¬aromyces pombe was evaluated as a candidate for these funct¬ions. Com¬par¬¬ative genomic analysis predicted a role in thiamin metabolism, not biosyn¬th¬esis, because free-standing homologues of this Nudix dom¬ain occur not only in fungi and plants, but also in proteo¬bacteria (whose thiamin biosynthesis pathway has no adenylated thiazole or thiamin monophosph¬ate hydrolysis steps) and animals (which do not make thiamin). Supporting this prediction, recomb¬¬inant Tnr3 and its Saccharo¬myces cerevisiae, Arabid¬opsis, and maize Nudix homo¬logues lacked thiamin monophosphate phos¬phatase activity but were active against ThDP, and up to 60-fold more active against diphos¬ph¬ates of the toxic thiamin degradation pro¬ducts oxy- and oxo¬thi¬amin. Deleti¬ng the S. cere¬visiae Nudix gene (YJR142W) lower¬ed oxythiamin resistance, over-expressing it rais¬ed resist¬ance, and express¬ing its plant or bacterial counterparts restored resist-ance to the YJR142W deletant. By converting the di¬phos¬phates of damaged forms of thiamin to monophosphates, the Tnr3 Nudix domain and its homologues can pre-empt the misincor¬p¬or¬ation of damaged diphosphates into ThDP-de¬pend¬ent enzymes, and the resulting toxicity