Potato Tuber Proteins Research Articles

Unveiling the presence of insulin-like antidiabetic proteins in potato: A wholesome food

A study was taken up to explore the possibilities for the presence of Insulin like protein in potato tubers. The serological based Direct antigen coating-Enzyme linked immune sorbent assay (DAC-ELISA) clearly detected and quantified the presence of insulin like proteins in dormant and sprouted potato tubers. Presence of ILP was further confirmed in dormant or sprouted potato tuber by Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis where an expected size of approximately 10 kDa corresponding to that of Insulin standard was recorded. In the second phase, an in vivo antihyperglycemic activity was carried out by administering the lyophilized powder derived from the tubers of Indian potato varieties to streptozotocin-induced diabetic rats. Among the varieties, Kufri Surya and Kufri Pushkar reduced the blood sugar level to 29.7% and 18% respectively, whereas, the metformin drug reduced the blood sugar level to 23.6%. In addition, the antioxidant and antidiabetic compounds (other than insulin like proteins) of the same varieties were also studies where Kufri Surya was found to be rich in nutrients and antidiabetic compounds. This is the first report on presence of insulin like proteins in the tubers of Indian potato varieties. The study presents a lead to explore the genes expressing insulin like proteins and subsequent utilization in developing specialty insulin rich potato varieties either by biotechnological based gene transfer approaches or by traditional breeding approach.

Nutritional Value and Sensory Quality of New Potatoes in Response to Silicon Application

Since silicon regulates plant physiological and biochemical processes, it was hypothesized that foliar silicon application could contribute to improving the quality of new potatoes. This paper analyzes the effect of silicon (sodium silicate) on the nutritional value and sensory quality of new potatoes. Silicon was applied at the dose of 23.25 g Si·ha−1 or 46.50 g Si·ha−1 once at the leaf development stage (BBCH 14–16) or at the tuber initiation stage (BBCH 40–41) and twice, at the leaf development and tuber initiation stages. Potatoes were harvested 75 days after planting (the end of June). Silicon had no effect on the dry matter, total sugars and monosaccharides, protein, L-ascorbic acid or nitrate content in new potato tubers, but it increased the starch content under water deficit conditions. The most starch was accumulated by tubers following the application of 46.50 g Si·ha−1 at the leaf development stage (BBCH 14–16). Silicon did not affect the color of tuber flesh after cooking.

Orphan Genes in Crop Improvement: Enhancing Potato Tuber Protein without Impacting Yield.

Qua-Quine Starch (QQS), an Arabidopsis thaliana orphan gene, and its interactor, Arabidopsis Nuclear Factor Y subunit C4 (AtNF-YC4), can increase the total leaf and seed protein in different plants. Despite their potential in developing protein-rich crop varieties, their influence on the protein content of the stem, modified stem, and tuber was never investigated. Potato (Solanum tuberosum) is one of the most valuable food crops worldwide. This staple food is rich in starch, vitamins (B6, C), phenolics, flavonoids, polyamines, carotenoids, and various minerals but lacks adequate proteins necessary for a healthy human diet. Here we expressed A. thaliana QQS (AtQQS) and overexpressed S. tuberosum NF-YC4 (StNF-YC4) in potatoes to determine their influence on the composition and morphological characteristics of potato tubers. Our data demonstrated higher protein and reduced starch content in potato tubers without significantly compromising the tuber yield, shape, and numbers, when QQS was expressed or StNF-YC4 was overexpressed. Publicly available expression data, promoter region, and protein-protein interaction analyses of StNF-YC4 suggest its potential functionality in potato storage protein, metabolism, stress resistance, and defense against pests and pathogens. The overall outcomes of this study support QQS and NF-YC4's potential utilization as tools to enhance tuber protein content in plants.

Purification and comparison of soluble and membrane-bound polyphenol oxidase from potato (Solanum tuberosum) tubers

Enzymatic browning greatly affects the quality of potato products. Polyphenol oxidase (PPO) is the enzyme mainly responsible for potato enzymatic browning. PPO has soluble polyphenol oxidase (sPPO) and membrane-bound polyphenol oxidase (mPPO) forms. In this study, the properties of sPPO and mPPO were investigated in potato tubers. The molecular weight of potato sPPO and mPPO were estimated to be 69 kDa in the form of homodimers in vivo. The mass spectrometry results showed that the purified sPPO and mPPO protein in potato tubers was mainly tr|M1BMR6 (Uniprot). The optimum pH for sPPO and mPPO was 6.5, and the optimum temperatures were 20 and 30 °C, respectively. The Michaelis constant (Km) and maximum unit enzyme activity (Vmax) of sPPO were 6.08 mM and 2161 U/S when catechol was used as the substrate, whereas those of mPPO were 2.95 mM and 2129.53 U/S, respectively. The mPPO had stronger affinity to the substrate catechol than sPPO, whereas pyrogallic acid was stronger affinity for sPPO. Ascorbic acid and sodium sulfite were inhibitors of sPPO and mPPO, respectively. After understanding the different binding states of polyphenol oxidase, different inhibitors and treatment methods can be used to treat the enzyme according to different enzymatic properties, so as to achieve a greater degree of Browning control. These results will provide a theoretical basis for regulating PPO activity to reduce enzymatic browning during potato processing.

Effect of potato apical leaf curl disease on glycemic index and resistant starch of potato (Solanum tuberosum L.) tubers

Tomato leaf curl New Delhi virus-potato (ToLCNDV-potato) causes potato apical leaf curl disease which severely affects nutritional parameters such as carbohydrate, protein, and starch biosynthesis thereby altering glycemic index (GI) and resistant starch (RS) of potato. ToLCNDV-potato virus was inoculated on potato cultivars (Kufri Pukhraj [susceptible]; Kufri Bahar [resistant]) and various quality parameters of potato tuber were studied. There was a significant (P < 0.01) reduction in starch, amylose and resistant starch contents in the infected tubers. However, carbohydrate and amylopectin increased significantly (P < 0.01) which contributes to increased starch digestibility reflected with high GI and glycemic load values. Besides, ToLCNDV-potato infection leads to a significant increase in reducing sugar, sucrose, amino acid and protein in potato tubers. This is a first-ever study that highlights the impact of biotic stress on GI, RS and nutritional quality parameters of potato which is a matter of concern for consumers.

Ratio of starch, protein, and glycoalkaloids in potato tubers during the growing season

Ratio of starch, protein, and glycoalkaloids in potato tubers during the growing season

Aggregation behavior of solubilized meat - Potato protein mixtures

Knowledge on the mixing behavior of meat and plant proteins is of importance for the manufacture of so-called hybrid products, a product category that is becoming of interest to food manufacturers. The aim of this study was to assess the pH-dependent miscibility and aggregation behavior in combinations of solubilized pork meat and potato tuber proteins. Analysis on their individual pH-dependent surface charge and size were followed by a visual and microscopic evaluation of their mixtures. Image analysis was used to obtain separation indices, aggregate areas, and aggregate aspect ratios and FTIR spectra were recorded to obtain insights into secondary structural elements. Net zero charge transition points differed, with a higher value for potato (pH 6.8) compared to meat proteins (pH 5.7). In mixtures, homogeneous solutions (pH 5.8 and 7.0) abruptly changed to phase-separated ones at low (pH 3) to medium (pH 5.5) pH. Here, anisotropic, clustered aggregates at high meat protein contents were exchanged for smaller, irregularly-shaped and sized microstructures at low ones and image analysis suggested a perturbing effect of potato on meat proteins to associate and form fibrous aggregates. The isoelectric point of salt-soluble meat proteins (pH ~ 5.5) was described as defining boundary value for co-solubility or interaction in between individual meat and meat and potato proteins. FTIR results confirmed alterations as a function of mixing ratio and pH. Results indicate that significant textural changes can be expected to occur in hybrid matrices, with plant proteins impeding the structural-self-association of meat proteins.

Possibility of Limiting Mineral Fertilization in Potato Cultivation by Using Bio-fertilizer and Its Influence on Protein Content in Potato Tubers

Potato protein is a valuable source of essential plant-derived amino acids, the composition of which is similar to that of chicken egg protein considering the amino acid reference. Many factors used in potato cultivation can modify its composition. The use of bio-fertilizers in potato growing offers a possibility of a better use of minerals from soil and organic sources and reducing the need for mineral fertilizers by activating minerals present in soil. The effect can be to improve not only the potato tuber yield but also the nutritional value. The aim of this study has been to determine the hanges in the content of crude protein and the composition of amino acids in potato tubers, depending on the application of the bio-fertilizer (UGmax), organic fertilizers (pea as a catch crop, straw, and farmyard manure (FYM)) as well as mineral fertilization (100% and 50% of the reference rate). The application of bio-fertilizer significantly increased the content of essential and non-essential amino acids in potato tuber protein. With the half-decreased mineral fertilization rate, bio-fertilizer most effectively increased the content of tyrosine, methionine, asparagine in potato tuber protein in the treatments with FYM or with a catch crop as well as without organic fertilization.

Total and True Protein Content in Potato Tubers Depending on Herbicides and Biostimulants

The aim of the study was to determine the effect of herbicides and herbicides used with biostimulants on the content of total and true protein in potato tubers. The three-year field experiment was carried out using the random two-way split-plot arrangement in three repetitions. The examined factors were: I—three cultivars of potato: Bartek, Gawin, Honorata; II—five method applications of herbicides and herbicides with biostimulants: 1. Control—mechanical weeding, 2. Harrier 295 ZC (linuron + clomazone), 3. Harrier 295 ZC + Kelpak SL (linuron + clomazone and extract from algae Ecklonia maxima), 4. Sencor 70 WG (metribuzin), 5. Sencor 70 WG + Asahi SL (metribuzin and sodium p-nitrophenolate, sodium o-nitrophenolate, sodium 5-nitroguolacolate). On the plots sprayed with herbicides and herbicides mixed with biostimulants, a significant increase in the content of total and true proteins and the share of true protein in total protein in relation to tubers harvested from the control object was found. Genetic features of cultivars determined the content of total and true protein in potato tubers. The highest total and true protein was accumulated by tubers of the Bartek cultivar, and the least by the Honorata cultivar.

Zawartość białka ogólnego i właściwego w bulwach ziemniaka w zmiennych warunkach pogodowych pod wpływem stosowanych biostymulatorów

Zawartość białka ogólnego i właściwego w bulwach ziemniaka w zmiennych warunkach pogodowych pod wpływem stosowanych biostymulatorów

A patatin-like protein synergistically regulated by jasmonate and ethylene signaling pathways plays a negative role in Nicotiana attenuata resistance to Alternaria alternata

Although patatin was initially identified as a major storage protein in potato tubers, patatin-like proteins (PLPs) have been recently reported to be widely present in many plant species and shown to be involved in plant-pathogen interactions. However, it is not clear whether PLPs are involved in Nicotiana attenuata resistance against the necrotrophic fungal pathogen, Alternaria alternata. In this study we identified a NaPLP gene, whose expression was highly elicited by A. alternata inoculation. Silencing NaPLP enhanced N. attenuata resistance to A. alternata, which was associated with higher induction levels of JA and ethylene biosynthetic genes, NaACS1, NaACO1 and NaLOX3. The induction of NaPLP expression by the fungus was abolished in JA-deficient plants and significantly reduced in ethylene-insensitive plants. In addition, NaPLP transcripts were highly induced by exogenous treatment with either methyl jasmonate (MeJA) or ethephon. Co-treatment with MeJA and ethephon led to a much higher induction level of NaPLP transcripts, and this synergistic induction was largely dependent on endogenous JA and ethylene signaling pathways. Thus, we conclude that the NaPLP gene is elicited by A. alternata via JA and ethylene signaling pathways in a synergistic way; however, unlike other JA- and ethylene-induced defense genes, NaPLP negatively affects plant resistance to the fungus likely by suppressing JA and ethylene biosynthetic gene expression.

Proteomic characterization and antifungal activity of potato tuber proteins isolated from starch production waste under different temperature regimes.

Proteins were obtained from effluent of a starch manufacture by using different isolation temperatures (40, 60, 80, and 100°C). The proteins, remaining in effluent after treatment of potato juice at 80 and 100°C differed significantly in composition and in structural stability as well as in trypsin inhibitory and antifungal activities in comparison with the variants of 40 and 60°C. The protein samples of 80°C exhibited the highest antifungal activity and its average value of IC50 against five strains of two Fusarium species was determined in average at 0.18mgml-1. The 80°C protein samples consisted predominantly of low-molecular proteins (7-17kDa) identified as potato tuber protease inhibitors I and II. Predominantly, protease inhibitors II were identified for the protein samples obtained by 100°C and here we identified 7 spots in comparison with 12 identified for the 80°C samples. Samples of 40 and 60°C with low antifungal activities represent high variability of detected and identified proteins. We identified various representatives of aspartic, cysteine, and serine protease inhibitors in both types of samples. These samples also contained Kunitz-type protease inhibitors that were not found in the 80 and 100°C samples which documented thermal unstableness of Kunitz-type protease inhibitors. Functional stability at high temperatures and antifungal activity of isolated potato protease inhibitors I and II support the potential of this fraction usage in food, feed, pharmaceutical, or agricultural industry and offer new products for starch manufactures. At the same time, utilization of the stable protein fraction of waste deproteinized potato water promotes exploitation of potato starch production resources.

Оценка сортов картофеля по урожайности и биохимическим показателям в условиях Кировской области

Potato is one of the most important foodstulfs for wide layers of population in the Russian Federation. Materials of 2014-2017 competitive testing investigation of potato varieties by productivity and basic biochemical parameters of tubers (the content of dry matter, starch, protein, vitamin C, and reducing sugars) in Kirov region are presented in the article. The objects of study are 9 varieties of two maturity groups: early and middle-early, mid ripening and middle-late. Perspective potato varieties of different terms of maturity combining high productivity and tuber quality have been selected. Within the first group the variety samples bred in Falenki breeding station are chosen: an early sample 179-10, which has an average productivity of 34.8 t/ha, addition to the standard Udacha (All-Russia Research Institute of Potato Farming) is 3.1 t/ha, addition to the standard Nevsky (North West Research Institute of Agriculture)- 8.8 t/ha, tubers are round, of white color, noted for uniformity in nest and good taste; a middle-early sample 90-09 with productivity of 30.6 t/ha and starch content 15.4%. In the second group - a middle sample 109-09 with productivity of 27.9 t/ha, maximum starch content 17%. Within recognized varieties, Chaika (Falenki breeding station) had a higher concentration of starch; a higher content of vitamin С was recorded in Viza (Falenki breeding station) and Nevsky; Viza and Gloriya (Falenki breeding station) have good taste. Varieties Virazh (Falenki breeding station), Nevsky, and sample 34-07 are good for chips production because of high content of dry matter and low content of reducing sugars. It has been established that higher humidity during the period of active tuber formation had a negative effect on the content of dry matter and protein in potato tubers (r = -0.88 and -0.89 respectively).

High Hydrostatic Pressure (HHP)-Induced Structural Modification of Patatin and Its Antioxidant Activities.

Patatin represents a group of homologous primary storage proteins (with molecular weights ranging from 40 kDa to 45 kDa) found in Solanum tuberosum L. This group comprises 40% of the total soluble proteins in potato tubers. Here, patatin (40 kDa) was extracted from potato fruit juice using ammonium sulfate precipitation (ASP) and exposed to high hydrostatic pressure (HHP) treatment (250, 350, 450, and 550 MPa). We investigated the effect of HHP treatment on the structure, composition, heat profile, and antioxidant potential, observing prominent changes in HHP-induced patatin secondary structure as compared with native patatin (NP). Additionally, significant (p < 0.05) increases in β-sheet content along with decreases in α-helix content were observed following HHP treatment. Thermal changes observed by differential scanning calorimetry (DSC) also showed a similar trend following HHP treatment; however, the enthalpy of patatin was also negatively affected by pressurization, and free sulfhydryl content and surface hydrophobicity significantly increased with pressurization up to 450 MPa, although both interactions progressively decreased at 550 MPa. The observed physicochemical changes suggested conformational modifications in patatin induced by HHP treatment. Moreover, our results indicated marked enhancement of antioxidant potential, as well as iron chelation activities, in HHP-treated patatin as compared with NP. These results suggested that HHP treatment offers an effective and green process for inducing structural modifications and improving patatin functionality.

Expression and assembly of cholera toxin B subunit and domain III of dengue virus 2 envelope fusion protein in transgenic potatoes

The rates of mosquito-transmitted dengue virus infection in humans have increased in tropical and sub-tropical areas. Domain III of dengue envelope protein (EDIII) is involved in cellular receptor binding and induces serotype-specific neutralizing antibodies. EDIII fused to the B subunit of Vibrio cholera (CTB–EDIII) was expressed in potatoes to develop a plant-based vaccine against dengue virus type 2. CTB–EDIII fused to an endoplasmic reticulum (ER) retention signal, SEKDEL, was introduced into potatoes by A. tumefaciens-mediated gene transformation. The integration of the CTB–EDIII fusion gene into the nuclear genome of transgenic plants was confirmed by genomic DNA polymerase chain reaction (PCR), and mRNA transcripts of CTB–EDIII were detected. CTB–EDIII fusion protein was expressed in potato tubers and assembled into a pentameric form capable of binding monosialotetrahexosylganglioside (GM1). The level of expression was determined to be ∼0.005% of total soluble protein in potato tubers. These results suggest that dengue virus antigen could be produced in potatoes, raising the possibility that edible plants are employed in mucosal vaccines for protection against dengue infection.

Development of Near-Infrared Reflection Spectroscopy Calibrations for Crude Protein and Dry Matter Content in Fresh and Dried Potato Tuber Samples

Potato tuber protein could be a valuable alternative in human and animal nutrition due to its adequate nutritional value and competitive protein yield per hectare. In this study, crude protein content (CPC) and dry matter content (DMC) of potato tuber samples (n = 117) prepared in different ways (fresh and dried samples) were analysed to develop practicable near-infrared reflection spectroscopy (NIRS) calibrations for CPC and DMC as well as for two different NIRS devices. The investigated potato samples showed a DMC between 14.1 and 35.2% and a CPC in the dry matter (DM) to vary between 4.93 and 12.31%, while CPC per fresh matter (FM) was between 1.43 and 2.87%. For dried potato flour, a NIRS calibration for CPC with a coefficient of determination of cross validation (R2CV) of 0.936 was developed and considered to be accurate for the prediction of this trait in potato tubers. Additionally, a NIRS calibration for DMC of fresh potatoes was developed with an R2CV value of 0.939. The newly developed NIRS calibration for CPC on fresh potato samples is useful for the selection of potato cultivars with comparatively high or low tuber protein content and demonstrates that a fast, simple, and cost-saving sample preparation leads to comparably adequate NIRS calibrations as those described in the literature using more extensive sample preparation methods.

Peptidomics of Peptic Digest of Selected Potato Tuber Proteins: Post-Translational Modifications and Limited Cleavage Specificity

Bioinformatic tools are useful in predicting bioactive peptides from food proteins. This study was focused on using bioinformatics and peptidomics to evaluate the specificity of peptide release and post-translational modifications (PTMs) in a peptic digest of potato protein isolate. Peptides in the protein hydrolysate were identified by LC-MS/MS and subsequently aligned to their parent potato tuber proteins. Five major proteins were selected for further analysis, namely, lipoxygenase, α-1,4-glucan phosphorylase, annexin, patatin, and polyubiquitin, based on protein coverage, abundance, confidence levels, and function. Comparison of the in silico peptide profile generated with ExPASy PeptideCutter and experimental peptidomics data revealed several differences. The experimental peptic cleavage sites were found to vary in number and specificity from PeptideCutter predictions. Average peptide chain length was also found to be higher than predicted with hexapeptides as the smallest detected peptides. Moreover, PTMs, particularly Met oxidation and Glu/Asp deamidation, were observed in some peptides, and these were unaccounted for during in silico analysis. PTMs can be formed during aging of potato tubers, or as a result of processing conditions during protein isolation and hydrolysis. The findings provide insights on the limitations of current bioinformatics tools for predicting bioactive peptide release from proteins, and on the existence of structural modifications that can alter the peptide bioactivity and functionality.

Cover Picture: Biotechnology Journal 11/2015

AbstractThis regular issue of BTJ features articles on the production of biofuels, small molecules and recombinant proteins. The cover is inspired by an article describing increased expression levels of recombinant proteins in potato tubers upon post‐harvest light treatment. © Lenslife – Fotolia.com

Variety-specificity of soluble proteins of potato tubers

Separation of soluble tuber proteins from six potato clones and twelve varieties cultivated in Poland has been accomplished by disc electrophoresis. It was found that electrophoretic pattern was unique for a given clone or variety. Data obtained confirm results of the other authors for the other varieties and indicate that electrophoretic analysis of potato tuber proteins can be a useful method for taxonomic studies. Such analysis however cannot be used for genetic research since no correlations were found between electrophoretic patterns and genetic origin of respective clones and varieties.

Novel in vitro inhibitory functions of potato tuber proteinaceous inhibitors.

Plant protease inhibitors are a structurally highly diverse and ubiquitous class of small proteins, which play various roles in plant development and defense against pests and pathogens. Particular isoforms inhibit in vitro proteases and other enzymes that are not their natural substrates, for example proteases that have roles in human diseases. Mature potato tubers are a rich source of several protease inhibitor families. Different cultivars have different inhibitor profiles. With the objective to explore the functional diversity of the natural diversity of potato protease inhibitors, we randomly selected and sequenced 9,600 cDNA clones originated from mature tubers of ten potato cultivars. Among these, 120 unique inhibitor cDNA clones were identified by homology searches. Eighty-eight inhibitors represented novel sequence variants of known plant protease inhibitor families. Most frequent were Kunitz-type inhibitors (KTI), potato protease inhibitors I and II (PIN), pectin methylesterase inhibitors, metallocarboxypeptidase inhibitors and defensins. Twenty-three inhibitors were functionally characterized after heterologous expression in the yeast Pichia pastoris. The purified recombinant proteins were tested for inhibitory activity on trypsin, eleven pharmacological relevant proteases and the non-proteolytic enzyme 5-lipoxygenase. Members of the KTI and PIN families inhibited pig pancreas elastase, β-Secretase, Cathepsin K, HIV-1 protease and potato 5-lipoxygenase. Our results demonstrate in vitro inhibitory diversity of small potato tuber proteins commonly known as protease inhibitors, which might have biotechnological or medical applications.Electronic supplementary materialThe online version of this article (doi:10.1007/s00438-014-0906-5) contains supplementary material, which is available to authorized users.