Research Update:Potato or Solanum tuberosum L.

  seminal trace...Potato Extract.10:1.Irish potato tubers,Solanum tuberosum L.Potatoes Extract.

 


   Phytochemical info of Potato or Solanum tuberosum L.

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   Research Update:Potato or Solanum tuberosum L.

  L-lactate metabolism in potato tuber mitochondria.:FEBS J. 2007 Mar;274(6):1459-69.Paventi G, Pizzuto R, Chieppa G, Passarella S.Dipartimento di Scienze per la Salute, Universit¨¤ del Molise, Via De Sanctis, 86100 Campobasso, Italy.

 We investigated the metabolism of L-lactate in mitochondria isolated from potato tubers grown and saved after harvest in the absence of any chemical agents. Immunologic analysis by western blot using goat polyclonal anti-lactate dehydrogenase showed the existence of a mitochondrial lactate dehydrogenase, the activity of which could be measured photometrically only in mitochondria solubilized with Triton X-100. The addition of L-lactate to potato tuber mitochondria caused: (a) a minor reduction of intramitochondrial pyridine nucleotides, whose measured rate of change increased in the presence of the inhibitor of the alternative oxidase salicyl hydroxamic acid; (b) oxygen consumption not stimulated by ADP, but inhibited by salicyl hydroxamic acid; and (c) activation of the alternative oxidase as polarographically monitored in a manner prevented by oxamate, an L-lactate dehydrogenase inhibitor. Potato tuber mitochondria were shown to swell in isosmotic solutions of ammonium L-lactate in a stereospecific manner, thus showing that L-lactate enters mitochondria by a proton-compensated process. Externally added L-lactate caused the appearance of pyruvate outside mitochondria, thus contributing to the oxidation of extramitochondrial NADH. The rate of pyruvate efflux showed a sigmoidal dependence on L-lactate concentration and was inhibited by phenylsuccinate. Hence, potato tuber mitochondria possess a non-energy-competent L-lactate/pyruvate shuttle. We maintain, therefore, that mitochondrial metabolism of L-lactate plays a previously unsuspected role in the response of potato to hypoxic stress.

  Combined effects of selenium and drought on photosynthesis and mitochondrial respiration in potato.:Plant Physiol Biochem. 2007 Feb;45(2):162-7. Epub 2007 Jan 20.Germ M, Kreft I, Stibilj V, Urbanc-Bercic O.National Institute of Biology, Vecna pot 111, SI-1111 Ljubljana, Slovenia.

 The possible effects of selenium (Se) foliar spraying and drought were studied for 3 months in potato (Solanum tuberosum L.) cultivar Desiree in Ljubljana, Slovenia. Four combinations of treatments were conducted: well-watered plants with and without Se foliar spraying, and drought exposed plants with and without Se foliar spraying. The following parameters were monitored 2 and 4 weeks after treatments: net photosynthesis, transpiration rate, quantum yield of photosystem II (PSII), and respiratory potential measured by electron transport system activity. After 3 months of treatments, leaf water potential and tuber yield were determined. The content of Se in tubers was measured after harvesting time. Several effects of drought and Se foliar spraying and their combinations were found. Net photosynthesis and respiratory potential were lower in drought exposed plants 4 weeks after treatments. Se induced higher respiratory potential in the leaves 4 weeks after treatments. Higher efficiency of energy conversion in PSII, expressed by a higher effective quantum yield, was observed in Se treated plants 2 weeks after treatments. Foliarly applied Se was efficiently absorbed by plant leaves and transported to the tubers.

  Andean potato cultivars (Solanum tuberosum L.) as a source of antioxidant and mineral micronutrients.:J Agric Food Chem. 2007 Jan 24;55(2):366-78.Andre CM, Ghislain M, Bertin P, Oufir M, Herrera Mdel R, Hoffmann L, Hausman JF, Larondelle Y, Evers D.Institut des Sciences de la Vie, Universit¨¦ catholique de Louvain, B-1348 Louvain-La-Neuve, Belgium. andre@lippmann.lu

 Potato tubers were evaluated as a source of antioxidants and minerals for the human diet. A genetically diverse sample of Solanum tuberosum L. cultivars native to the Andes of South America was obtained from a collection of nearly 1000 genotypes using microsatellite markers. This size-manageable collection of 74 landraces, representing at best the genetic diversity among potato germplasm, was analyzed for iron, zinc, calcium, total phenolic, total carotenoid, and total vitamin C contents. The hydrophilic antioxidant capacity of each genotype was also measured using the oxygen radical absorbance capacity (ORAC) assay. The iron content ranged from 29.87 to 157.96 microg g-1 of dry weight (DW), the zinc content from 12.6 to 28.83 microg g-1 of DW, and the calcium content from 271.09 to 1092.93 microg g-1 of DW. Total phenolic content varied between 1.12 and 12.37 mg of gallic acid equiv g-1 of DW, total carotenoid content between 2.83 and 36.21 microg g-1 of DW, and total vitamin C content between 217.70 and 689.47 microg g-1 of DW. The range of hydrophilic ORAC values was 28.25-250.67 micromol of Trolox equiv g-1 of DW. The hydrophilic antioxidant capacity and the total phenolic content were highly and positively correlated (r = 0.91). A strong relationship between iron and calcium contents was also found (r = 0.67). Principal component analysis on the studied nutritional contents of the core collection revealed that most potato genotypes were balanced in terms of antioxidant and mineral contents, but some of them could be distinguished by their high level in distinct micronutrients. Correlations between the micronutrient contents observed in the sample and the genetic distances assessed by microsatellites were weakly significant. However, this study demonstrated the wide variability of health-promoting micronutrient levels within the native potato germplasm as well as the significant contribution that distinct potato tubers may impart to the intake in dietary antioxidants, zinc, and iron.

  Analysis of sphingolipids in potatoes (Solanum tuberosum L.) and sweet potatoes (Ipomoea batatas (L.) Lam.) by reversed phase high-performance liquid chromatography electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS)..:Mol Nutr Food Res. 2006 Dec;50(12):1201-11. Bartke N, Fischbeck A, Humpf HU.Institut f¨¹r Lebensmittelchemie, Westf?lische Wilhelms-Universit?t M¨¹nster, M¨¹nster, Germany.

 Ceramides and glucocerebrosides of potatoes (Solanum tuberosum L.) and sweet potatoes (Ipomoea batatas (L.) Lam.) were analyzed using RP-HPLC-ESI-MS/MS. Ceramides and glucocerebrosides containing the three different long-chain bases 4,8-sphingadienine (d18:2(delta4,delta8)), 4-hydroxy-8-sphingenine (t18:1(delta8)), and 8-sphingenine (d18:1(delta8)) acylated to saturated and unsaturated hydroxy- and nonhydroxy fatty acids with 16-26 carbon atoms were detected. For ceramides and glucocerebrosides 4,8-sphingadienine (d18:2(delta4,delta8)) was found as the major long-chain base, with lesser amounts of 4-hydroxy-8-sphingenine (t18:1(delta8)) and 8-sphingenine (d18:1(delta8)). 2-(Alpha-)hydroxypalmitic acid (C16:0h) was the major fatty acid, which was found to be acylated to the long-chain bases. For quantification of these compounds, an RP-HPLC-ESI-MS/MS method with an "echo-peak"-technique simulating internal standard injection was developed. The analyzed samples of potatoes and sweet potatoes showed amounts of approximately 0.1-8 microg/kg single ceramides and amounts up to 500 microg/kg glucocerebrosides, with C16:0h-glucosyl-4,8-sphingadienine as the major component.

  Potato (Solanum tuberosum L.).:Methods Mol Biol. 2006;344:25-36.Millam S.Institute of Molecular Plant Science, University of Edinburgh, EH9 3JR, The United Kingdom.

 Potato (Solanum tuberosum L.) is a globally important crop plant producing high yields of nutritionally valuable food in the form of tubers. It has been the focus of substantial study because of its use both as a staple food crop and as a potentially significant source of compounds of interest. This has included the development and application of transgenic technology for introducing novel traits of fundamental and applied interest. This chapter describes a rapid, efficient, and cost-effective system for the routine transformation of this crop plant at rates above 40% efficiency, calculated as the mean number of Southern blot- confirmed independent transgenics per number of internodal explants originally plated. Internodal sections are co-cultivated with Agrobacterium tumefaciens and subjected to a two-stage callus induction/shoot outgrowth system under kanamycin selection. Shoot regeneration rates are high using the described method, and excised independent shoots rooting from the cut end of the stem after two further subcultures on kanamycin are 95% certain to be transformed. The transgenic status can be confirmed by molecular analysis and the plants grown on for tuber production enabling a wide spectrum of further studies.


  Utility of pentose colorimetric assay for the purification of potato lectin, an arabinose-rich glycoprotein.:Glycoconj J. 2006 Nov;23(7-8):481-8.Pramod SN, Venkatesh YP.Department of Biochemistry & Nutrition, Central Food Technological Research Institute (CFTRI), Mysore, 570 020, Karnataka State, India. venkatyp@yahoo.com

 Potato lectin (Solanum tuberosum agglutinin, STA) is an unusual glycoprotein containing approximately 50% carbohydrates by weight. Of the total carbohydrates, 92% is contributed by L: -arabinose, which are O-linked to hydroxyproline residues. The ferric chloride-orcinol assay (Bial's test), which is specific for pentoses has so far been used only for the determination of free pentoses in biological samples. However, this colorimetric assay has not been used for the detection of pentoses in bound form as it occurs in Solanaceae lectins (potato, tomato, and Datura lectins). Utilizing the pentose colorimetric assay for monitoring the presence of potato lectin, a simpler and shorter procedure for the purification of this lectin from potato tubers has been developed. The yield of potato lectin (1.73 mg per 100 g potato tuber) is twice compared to the yields reported in earlier procedures. Although potato lectin is well known for its specificity to free trimers and tetramers of N-acetyl-D: -glucosamine (GlcNAc), it possesses a similar specificity to the core (GlcNAc)(2) of N-linked glycoproteins. The utilization of the pentose assay in the purification of arabinose-rich lectins/agglutinins obviates the necessity for the use of agglutination assay in the various purification steps. The pentose assay appears to be a simple and convenient colorimetric assay for detecting any pentose-rich glycoprotein in plant extracts. The utility of the pentose assay appears to have a significant potential in the detection of hydroxyproline-rich glycoproteins (HRGPs), which are generally O-arabinosylated.

  Red potato extract protects from D-galactosamine-induced liver injury in rats.:Biosci Biotechnol Biochem. 2006 Sep;70(9):2285-8. Epub 2006 Sep 7.

 The protective effects of red potato extract (RPE) as to liver damage were determined in D-galactosamine (GalN)-intoxicated rats. Increases in serum aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase activities, all of which were induced by GalN injection, decreased in RPE administered rats, suggesting that RPE acts as a functional food showing anti-hepatotoxicity.

  Glycoalkaloid development during greening of fresh market potatoes (Solanum tuberosum L.).:J Agric Food Chem. 2006 Aug 9;54(16):5847-54.Grunenfelder LA, Knowles LO, Hiller LK, Knowles NR.Postharvest Physiology and Biochemistry Lab, Department of Horticulture and Landscape Architecture, Washington State University, Pullman, 99164-6414, USA.

 Chlorophyll and glycoalkaloid synthesis in potato (Solanum tuberosum L.) tubers occur in direct response to light. The two processes are concurrent, but independent. Color photographic indices to subjectively grade fresh market potatoes for the extent of greening were developed under lighting conditions consistent with those of retail markets. Total glycoalkaloid (TGA) and chlorophyll accumulation for four cultivars were determined over the respective greening scales, thus calibrating the scales for TGA content. On average, TGA concentrations in complete longitudinal sections of tubers (flesh samples) were highest in Dark Red Norland followed by Russet Norkotah, Yukon Gold, and White Rose. TGA concentrations of flesh samples of White Rose and Yukon Gold tubers were somewhat variable and did not increase in direct proportion to greening level and chlorophyll content, particularly at higher levels of greening. TGA concentrations in Dark Red Norland and Russet Norkotah tubers were highly correlated (P < or = 0.001) with greening level and chlorophyll concentrations. When averaged over greening levels, skin samples contained 3.4- to 6.8-fold higher concentrations of TGAs than flesh samples, depending on the cultivar. The TGA concentration in periderm samples ranged from 37 to 160 mg/100 g of dry wt. Regardless of greening level, concentrations of TGAs in the flesh samples (including attached periderm) remained within limits presumed safe for human consumption. Discrimination of greened tubers on the basis of perceived glycoalkaloid toxicity is likely unfounded for the cultivars and greening levels studied.

  Immunolocalisation of two tropinone reductases in potato (Solanum tuberosum L.) root, stolon, and tuber sprouts.:Planta. 2006 Dec;225(1):127-37. Epub 2006 Jul 15.Kaiser H, Richter U, Keiner R, Brabant A, Hause B, Dr?ger B.Institute of Pharmaceutical Biology and Pharmacology, Martin-Luther-University Halle-Wittenberg, Hoher Weg 8, 06120 Halle/Saale, Germany.

 Tropinone reductases (TRs) are essential enzymes in the tropane alkaloid biosynthesis, providing either tropine for hyoscyamine and scopolamine formation or providing pseudotropine for calystegines. Two cDNAs coding for TRs were isolated from potato (Solanum tuberosum L.) tuber sprouts and expressed in E. coli. One reductase formed pseudotropine, the other formed tropine and showed kinetic properties typical for tropine-forming tropinone reductases (TRI) involved in hyoscyamine formation. Hyoscyamine and tropine are not found in S. tuberosum plants. Potatoes contain calystegines as the only products of the tropane alkaloid pathway. Polyclonal antibodies raised against both enzymes were purified to exclude cross reactions and were used for Western-blot analysis and immunolocalisation. The TRI (EC 1.1.1.206) was detected in protein extracts of tuber tissues, but mostly in levels too low to be localised in individual cells. The function of this enzyme in potato that does not form hyoscyamine is not clear. The pseudotropine-forming tropinone reductase (EC 1.1.1.236) was detected in potato roots, stolons, and tuber sprouts. Cortex cells of root and stolon contained the protein; additional strong immuno-labelling was located in phloem parenchyma. In tuber spouts, however, the protein was detected in companion cells.

  Metabolism of [14C]-2,4-dichlorophenol in edible plants.:Pest Manag Sci. 2006 Jun;62(6):558-64.Laurent F, Debrauwer L, Pascal-Lorber S.INRA, UMR X¨¦nobiotiques, 180 Ch. de Tournefeuille, BP3, F-31931 Toulouse Cedex 9, France. flaurent@toulouse.inra.fr

 Several 2,4-dichlorophenoxyacetic acid (2,4-D)-sensitive plants have been modified by genetic engineering with tfdA gene to acquire 2,4-D tolerance. The expression product of this gene degrades 2,4-D to 2,4-dichlorophenol (DCP), which is less phytotoxic but could cause a problem of food safety. After a comparison of 2,4-D and DCP metabolism in transgenic 2,4-D-tolerant and wild cotton (Gossypium hirsutum L.), a direct study of DCP metabolism in edible plants was performed. After petiolar uptake of a [U-phenyl-(14)C]-DCP solution followed by a 48 h water chase, aqueous extracts were analysed by high-performance liquid chromatography. Metabolites were thereafter isolated and their structural identities were determined by enzymatic and chemical hydrolyses and mass spectrometry analyses. The metabolic fate of DCP was equivalent to 2,4-D metabolism in transgenic 2,4-D-tolerant cotton. In addition, DCP metabolism was similar in transgenic and wild cotton. The major terminal metabolites were DCP-saccharide conjugates in all species, essentially DCP-(6-O-malonyl)-glucoside or its precursor DCP-glucose. The significance of this metabolic pathway with regard to food safety is discussed.


  Regulatory role of polyamine in the acid phosphatase from potato tubers.:Plant Physiol Biochem. 2006 Jan;44(1):43-8. Epub 2006 Feb 28.

 Effects of polyamine and metal ions on the new type of acid phosphatase purified from potato (Solanum tuberosum L. Irish Cobbler) tubers were analyzed. The enzyme belongs to nonspecific acid phosphatase family (EC 3.1.3.2), which hydrolyzes various phosphorylated substrates. The enzyme hydrolyzed inorganic pyrophosphate as a preferred substrate, and exhibited the hyperbolic kinetics with respect to the substrate, inorganic pyrophosphate in the absence of metal cations. Polyamine activated the enzyme effectively by lowering the K(m) value without appreciable changes in the maximal velocity. The most effective polyamines as activators were spermine and spermidine. Mg(2+) ion increased the K(m) value without affecting the maximal velocity of the enzyme, but Ca(2+) ion decreased both the K(m) and V(max) values. Increasing concentrations of spermine also decreased the K(m) value irrespective of Mg(2+) ion included, but gave a constant K(m) and V(max) values in the absence and presence of Ca(2+) ion. Action of spermine and metal ions can be explained by the complex formation with the substrate pyrophosphate. The acid phosphatase from potato can utilize the pyrophosphate-spermine or pyrophosphate-Ca(2+) complex as the preferred substrates. However, the enzyme can use the pyrophosphate-Mg complex with a weak affinity for the active site. Polyamine activates acid phosphatase in the absence and presence of metal cations, and activation by polyamine of the enzyme may contribute to the stimulation of starch biosynthesis and the control of glycolysis/gluconeogenesis by regulating PPi levels in growing potato tubers.

  Determination of organophosphorus pesticides in cucumber and potato by stir bar sorptive extraction.:J Chromatogr A. 2005 Nov 18;1095(1-2):1-7. Epub 2005 Oct 5. Liu W, Hu Y, Zhao J, Xu Y, Guan Y.Department of Analytical Chemistry and Micro-Instrumentation, Dalian Institute of Chemical Physics, Chinese Academy of Sciences.

 Organophosphorus pesticides (OPPs) in vegetables were determined by stir bar sorptive extraction (SBSE) and capillary gas chromatography with thermionic specific detection (TSD). Hydroxy-terminated polydimethylsioxane (PDMS) prepared by sol-gel method was used as extraction phase. The effects of extraction temperature, salting out, extraction time on extraction efficiency were studied. The detection limits of OPPs in water were < or = 1.2 ng/l. This method was also applied to the analysis of OPPs in vegetable samples and matrix effect was studied. Linear ranges of OPPs in vegetable samples were 0.05-50 ng/g with detection limits < or =0.15 ng/g and the repeatability of the method was less than 20% relative standard deviation.

  Effects of antisense acid invertase gene on reducing sugar and starch contents of potato (Solanum tuberosum L.) tuber stored at low temperature.:Zhi Wu Sheng Li Yu Fen Zi Sheng Wu Xue Xue Bao. 2005 Oct;31(5):533-8. Chinese.Wang Q, Huang HY, Zhang JW, Li XC.College of Agronomy, Gansu Agricultural University, Lanzhou 730070, China.

 Two transgenic potato lines with antisense AcInv gene and the non-transgenic varieties were used to test the reducing sugar and starch contents. The results indicated that the reducing sugar content increased and total starch content decreased in all samples after tubers were stored at 4 degrees C for 40 d. The reducing sugar content in tubers of transgenic line "Anti-AcInv Atlantic" and "Anti-AcInv Gannongshu No.2" were lower about 23% and 18% than those of Atlantic and Gannongshu No.2 (Table 1). The total starch and the amylopectin were also decreased by 1% and 1.3% in "Anti-AcInv Atlantic" and 1.4% and 1.7% in "Anti-AcInv Gannongshu No.2" respectively (Table 2). The proportions of amylose and amylopectin were lower in the transgenic lines than the non-transgenic varieties (Figs. 1 and 2). It was only 0.29 for "Anti-AcInv Atlantic" and 0.38 for "Anti-AcInv Gannongshu No.2". Meanwhile, there are fewer dark blue starch particles in transgenic tuber, which is less than in tuber of the non-transgenic varieties by paraffin-cut section method (Fig. 3). After the tubers were transferred to the storage temperature 15-17 degrees C for 20 d, the reducing sugar contents in tubers of the two transgenic lines were significantly lower than that of non-transgenic varieties. It was 0.23% for "Anti-AcInv Atlantic" and 0.24% for "Anti-AcInv Gannongshu No.2" (Table 1). It is suggested that the trans-antisense AcInv gene in the transgenic potato down-regulates the AcInv gene expression after the tubers were stored under low temperature.

  Liquid-liquid systems for acid hydrolysis of glycoalkaloids from Solanum tuberosum L. tuber sprouts and solanidine extraction.:Med Sci Monit. 2005 Jul;11(7):BR200-5. Epub 2005 Jun 29.Nikolic NC, Stankovic MZ, Markovic DZ.Faculty of Technology, University of Nish, Leskovac, Serbia and Montenegro. nikolac_n2002@yahoo.com

 BACKGROUND: Potato sprouts (Solanum tuberosum L.) contain steroidal glycoalkaloids containing solanidine, an important precursor for hormone synthesis. Glycoalkaloids are reported to inactivate the Herpes simplex, Herpes zoster and Herpes genitalis viruses in humans, while Aglyones, including solasodine, may protect against skin cancer. Extracts of glycoalkaloids or solanidine can be used to obtain a potential skin cancer preparation for clinical research. MATERIAL/METHODS: Dried potato sprouts were used to obtain glycoalkaloids and solanidine. The hydrolysis of glycoalkaloids in a liquid-liquid system was performed using a reflux condenser, obtaining extracts of glycolakaloids from dried and milled potato tuber sprouts. Hydrochloric acid was then added to the extract to form the first (aqueous) phase, and chloroform, trichloroethylene or carbon tetrachloride to form the second (organic) phase of the liquid-liquid system. In this way, glycoalkaloid hydrolysis to solanidine and solanidine extraction in the organic liquid phase were combined into a single step. IR and GC/MS analysis of solanidine was also conducted. RESULTS: Based on the results we obtained, the optimal liquid-liquid system was found to be 2% w/v hydrochloric acid in a 50% (volume) methanolic extract of glycoalkaloids from tuber sprouts, as the first phase, and chloroform as the second phase. Using this system, a yield of 1.46 g solanidine per 100 g of dried potato sprouts can be achieved. CONCLUSIONS: Glycoalkaloid hydrolysis in a liquid-liquid system yields the aglycone solanidine can be obtained from dried potato sprouts. The yield of solanidine is higher than that obtained using solid-liquid-liquid systems for glycoalkaloid hydrolysis from potato vines.

  Free and conjugated forms of salicylic acid: content and role in potato.:Prikl Biokhim Mikrobiol. 2005 May-Jun;41(3):354-7. Russian.Panina IaS, Vasiukova NI, Ozeretskovskaia OL.

 Hydrolysis of conjugated forms of salicylic acid and accumulation of its free form was observed after infection of potato tubers (Solanum tuberosum L.) with an incompatible race of phytophthora or treatment with an elicitor (chitosan). Infection of tubers with a compatible race of the pathogen or treatment with a suppressor (laminarin) decreased both the degree of hydrolysis of conjugated forms of salicylic acid and the accumulation of its free form.


  Antimicrobial activity studies on a trypsin-chymotrypsin protease inhibitor obtained from potato.:Biochem Biophys Res Commun. 2005 May 13;330(3):921-7.Kim JY, Park SC, Kim MH, Lim HT, Park Y, Hahm KS.Research Center for Proteineous Materials (RCPM), Chosun University, 375 Seosuk-Dong, Dong-Ku, Kwangju 501-759, Republic of Korea.

 A 5.6 kDa trypsin-chymotrypsin protease inhibitor was isolated from the tubers of the potato (Solanum tuberosum L cv. Gogu) by extraction of the water-soluble fraction, dialysis, ultrafiltration, and C18 reversed-phase high performance liquid chromatography. This inhibitor, which we named potamin-1 (PT-1), was thermostable and possessed antimicrobial activity but lacked hemolytic activity. PT-1 strongly inhibited pathogenic microbial strains, including Candida albicans, Rhizoctonia solani, and Clavibacter michiganense subsp. michiganinse. Automated Edman degradation showed that the N-terminal sequence of PT-1 was NH2-DICTCCAGTKGCNTTSANGAFICEGQSDPKKPKACPLNCDPHIAYA-. The sequence had 62% homology with a serine protease inhibitor belonging to the Kunitz family, and the peptide inhibited chymotrypsin, trypsin, and papain. This protease inhibitor, PT-1, was composed of polypeptide chains joined by disulfide bridge(s). Reduced PT-1 almost completely lost its activity against fungi and proteases indicating that disulfide bridge is essential for its protease inhibitory and antifungal activity. These results suggest that PT-1 is an excellent candidate as a lead compound for the development of novel oral or other anti-infective agents.

  Effect of selenate supplementation on glycoalkaloid content of potato (Solanum tuberosum L.).:J Agric Food Chem. 2004 Nov 17;52(23):7139-43.Turakainen M, V??n?nen T, Anttila K, Ollilainen V, Hartikainen H, Sepp?nen M.Department of Applied Biology, Post Office Box 27, FIN-00014, University of Helsinki, Finland.

 Potatoes (Solanum tuberosum L.) supplemented with increasing amounts of sodium selenate were analyzed for glycoalkaloid (GA) content. GAs were extracted with 5% acetic acid from freeze-dried tubers of two potato cultivars, Satu and Sini, harvested 10 weeks after planting as immature. The GAs alpha-solanine and alpha-chaconine were quantified by reverse-phase high-performance liquid chromatography (RP-HPLC) with diode array detection. Two independent experiments were performed. In the first experiment, the total GA concentration +/- standard error of the tubers ranged between 105 +/- 9 and 124 +/- 10 mg kg(-1) fresh weight in Satu and between 194 +/- 26 and 228 +/- 10 mg kg(-1) fresh weight in Sini. The ratio of alpha-solanine to alpha-chaconine was 0.2 in Satu and 0.5-0.6 in Sini. In the second experiment, the total GA concentration +/- standard error was 75 +/- 4 to 96 +/- 11 mg kg(-1) fresh weight, and the ratio of alpha-solanine to alpha-chaconine was 0.3-0.4 in Satu. A high sodium selenate supplementation (0.9 mg of Se kg(-1) quartz sand) slightly decreased the GA content in Satu, but this decrease was not statistically significant. Furthermore, at this addition level the Se concentration increased to a very high level of 20 microg g(-1) dry weight, which cannot be recommended for human consumption. In both experiments, the Se concentration in tubers increased with increasing sodium selenate application levels. Our results show that acceptable application levels of selenate did not have an effect on the GA concentration in immature potato tubers.

  Metabolic engineering of high carotenoid potato tubers containing enhanced levels of beta-carotene and lutein.:J Exp Bot. 2005 Jan;56(409):81-9. Epub 2004 Nov 8.Ducreux LJ, Morris WL, Hedley PE, Shepherd T, Davies HV, Millam S, Taylor MA.Quality, Health and Nutrition, Scottish Crop Research Institute, Invergowrie, Dundee, DD2 5DA, UK.

 In order to enhance the carotenoid content of potato tubers, transgenic potato plants have been produced expressing an Erwinia uredovora crtB gene encoding phytoene synthase, specifically in the tuber of Solanum tuberosum L. cultivar Desiree which normally produces tubers containing c. 5.6 microg carotenoid g(-1) DW and also in Solanum phureja L. cv. Mayan Gold which has a tuber carotenoid content of typically 20 microg carotenoid g(-1) DW. In developing tubers of transgenic crtB Desiree lines, carotenoid levels reached 35 microg carotenoid g(-1) DW and the balance of carotenoids changed radically compared with controls: beta-carotene levels in the transgenic tubers reached c. 11 microg g(-1) DW, whereas control tubers contained negligible amounts and lutein accumulated to a level 19-fold higher than empty-vector transformed controls. The crtB gene was also transformed into S. phureja (cv. Mayan Gold), again resulting in an increase in total carotenoid content to 78 microg carotenoid g(-1) DW in the most affected transgenic line. In these tubers, the major carotenoids were violaxanthin, lutein, antheraxanthin, and beta-carotene. No increases in expression levels of the major carotenoid biosynthetic genes could be detected in the transgenic tubers, despite the large increase in carotenoid accumulation. Microarray analysis was used to identify a number of genes that were consistently up- or down-regulated in transgenic crtB tubers compared with empty vector controls. The implications of these data from a nutritional standpoint and for further modifications of tuber carotenoid content are discussed.

  Subtilisin protein inhibitor from potato tubers.:Biochemistry (Mosc). 2004 Oct;69(10):1092-8.Revina TA, Speranskaya AS, Kladnitskaya GV, Shevelev AB, Valueva TA.Bach Institute of Biochemistry, Russian Academy of Sciences, Leninskii pr. 33, Moscow 119071, Russia.

 A protein with molecular weight of 21 kD denoted as PKSI has been isolated from potato tubers (Solanum tuberosum L., cv. Istrinskii). The isolation procedure includes precipitation with (NH4)2SO4, gel chromatography on Sephadex G-75, and ion-exchange chromatography on CM-Sepharose CL-6B. The protein effectively inhibits the activity of subtilisin Carlsberg (Ki = 1.67 +/- 0.2 nM) by stoichiometric complexing with the enzyme at the molar ratio of 1 : 1. The inhibitor has no effect on trypsin, chymotrypsin, and the cysteine proteinase papain. The N-terminal sequence of the protein consists of 19 amino acid residues and is highly homologous to sequences of the known inhibitors from group C of the subfamily of potato Kunitz-type proteinase inhibitors (PKPIs-C). By cloning PCR products from the genomic DNA of potato, a gene denoted as PKPI-C2 was isolated and sequenced. The N-terminal sequence (residues from 15 to 33) of the protein encoded by the PKPI-C2 gene is identical to the N-terminal sequence (residues from 1 to 19) of the isolated protein PKSI. Thus, the inhibitor PKSI is very likely encoded by this gene.

  Determination of copper, zinc, selenium, lead and cadmium in potatoes (Solanum tuberosum L.) using potentiometric stripping methods.:Food Addit Contam. 2004 Jul;21(7):649-57.Dugo G, La Pera L, Lo Turco V, Giuffrida D, Restuccia S.Department of Organic and Biological Chemistry, University of Messina, Salita Sperone 31, I-98166 Messina, Italy. dugogia@isengard.unime.it

 Potentiometric stripping analysis was used to determine simultaneously the content of zinc(II), cadmium(II), lead(II) and copper(II) in potatoes, whereas the concentration of selenium was determined by cathodic stripping potentiometric analysis. Metal cations were extracted from potatoes by hydrogen peroxide/hydrochloric acid treatments. The relative standard deviation of the methods ranged from 2.3 to 4.1% and the detection limits were lower than 2.5 microg kg(-1). The results obtained with the proposed methods were compared with those obtained with graphite furnace atomic absorption spectroscopy, a common method for determining metals. The results of the two methods agreed to within 6.1%. Twelve samples of yellow flesh potatoes from different cultivars were analysed. Of all the metals determined, Cu and Zn were the most abundant with concentrations between 0.5 and 4.6 mg kg(-1). Selenium was only found in three samples in very low amounts (<0.1 mg kg(-1)), whilst Pb and Cd concentrations were in the range 0.01-0.27 mg kg(-1).


  An allele of dihydroflavonol 4-reductase associated with the ability to produce red anthocyanin pigments in potato (Solanum tuberosum L.).:Theor Appl Genet. 2003 Nov;107(8):1375-83. Epub 2003 Sep 3.De Jong WS, De Jong DM, De Jong H, Kalazich J, Bodis M.Department of Plant Breeding, Cornell University, Ithaca, NY 14853-1901, USA. wsd2@cornell.edu

 The potato R locus is necessary for the production of red pelargonidin-based anthocyanin pigments in any tissue of the plant, including tuber skin and flower petals. The production of pelargonidins in plants requires the activity of dihydroflavonol 4-reductase (DFR) to catalyze the reduction of dihydrokaempferol into leucopelargonidin. To test the hypothesis that potato R encodes DFR, portions of both dfr alleles were sequenced from a diploid potato clone known to be heterozygous Rr. Sequence comparison revealed a polymorphic BamHI restriction site. The presence or absence of this site was monitored in three diploid populations that segregated for R, as well as in a wide range of tetraploid breeding clones and cultivars, by amplifying a fragment of dfr and digesting the products with BamHI. An identically sized dfr restriction fragment lacking the BamHI site was present in all potato clones that produced red anthocyanin pigments, while the same fragment was absent in many potato clones with white tuber skin and flowers. An independent RFLP test using DraI to detect sequence polymorphism was performed on a subset of the potato clones. This test also revealed dfr-derived bands that were present in all red-colored potatoes and absent in several white clones. The presence of shared restriction fragments in all red-colored potatoes provides strong evidence that R does indeed code for DFR. The data are also consistent with a 48 year-old hypothesis by Dodds and Long, that R was selected just once during the domestication of potato. A cDNA clone corresponding to the red allele of dfr was sequenced and compared to two other alleles. The red allele is predicted to encode a 382 amino acid protein that differs at ten amino acid positions from the gene products of the two alternative alleles. Several of these differences map in a region known to influence DFR substrate specificity in Gerbera.

  Wounding stress increases the phenolic content and antioxidant capacity of purple-flesh potatoes (Solanum tuberosum L.).:J Agric Food Chem. 2003 Aug 27;51(18):5296-300.Reyes LF, Cisneros-Zevallos L.Department of Horticultural Sciences, Texas A&M University, College Station, Texas 77843-2133, USA.

 Several abiotic stresses, including ethylene, methyl jasmonate, temperature, light, and wounding, were tested for their ability to induce accumulation of phenolic compounds and antioxidant capacity in purple-flesh potatoes (cv. All Blue). Results indicated that temperature, ethylene, methyl jasmonate, and light treatments did not significantly affect the accumulation of phenolic compounds compared to control samples. Only tubers with low initial anthocyanin levels treated with methyl jasmonate showed approximately 60% anthocyanin accumulation. Wounding induced the accumulation of phenolics compounds and an increase of PAL-activity in sliced tissue compared to the control. Total phenolics increased approximately 60% with a parallel 85% increase in antioxidant capacity. These results show that selection of appropriate abiotic stresses can enhance the nutritional and functional value of potatoes.

  Lipid and oxylipin profiles during aging and sprout development in potato tubers (Solanum tuberosum L.).:Biochim Biophys Acta. 2003 Jul 21;1633(2):118-26.Fauconnier ML, Welti R, Bl¨¦e E, Marlier M.Unit¨¦ de Chimie G¨¦n¨¦rale et Organique, Facult¨¦ Universitaire des Sciences Agronomiques de Gembloux, Passage des D¨¦port¨¦s 2, B-5030, Gembloux, Belgium. fauconnier.ml@fsagx.ac.be

 Potato tubers (Solanum tuberosum L. cv Bintje) were stored at 20 degrees C for 210 days without desprouting to study the lipoxygenase pathway during aging. After 15 days of storage, potato tubers sprouted, while after 45-60 days, apical dominance was lost and multiple sprouts developed. Analysis of the fatty acid hydroperoxides (HPOs) revealed that 9-S-hydroperoxide of linoleic acid (9-HPOD) was the main oxylipin formed. Between 45 and 60 days of storage, increases in the levels of 9-HPOD and colneleic acid were observed. Analysis of phospholipids and galactolipids by electrospray ionisation tandem mass spectrometry (ESI-MS/MS) showed that a decrease in the levels of phosphatidylcholine (PC), phosphatidylethanolamine (PE), phosphatidylinositol (PI), digalactosyldiacylglycerol (DGDG), and monogalactosyldiacylglycerol (MGDG) occurred between 0 and 45 days of aging. The decrease in the amount of linoleic acid in complex lipids correlates well with the amount of 9-HPOD and colneleic acid produced.

  Purification of a polyphenol oxidase isoform from potato (Solanum tuberosum) tubers.:Phytochemistry. 2003 Aug;63(7):745-52.Marri C, Frazzoli A, Hochkoeppler A, Poggi V.Department of Industrial Chemistry, University of Bologna, Viale Risorgimento 4, I-40136 Bologna, Italy.

 A different expression pattern of polyphenol oxidases has been observed during storage in cultivars of potato (Solanum tuberosum L.) featuring different length of dormancy: a short-dormant cultivar showed, at the end of the dormancy, both the highest polyphenol oxidase activity and the largest number of enzyme isoforms. An isoform of polyphenol oxidase isolated at the end of the physiological dormancy from a short-dormant cultivar has been purified to homogeneity by means of column chromatography on phenyl Sepharose and on Superdex 200. The purification factor has been determined equal to 88, and the molecular mass of the purified isoform has been estimated to be 69 and 340 kDa by SDS polyacrylamide gel electrophoresis and gel filtration on Superdex 200, respectively, indicating this PPO isoform as a multimer. The corresponding zymogram features a diffused single band at the cathodic region of the gel and the pI of this polyphenol oxidase has been calculated equal to 6.5.

  Patatin, the tuber storage protein of potato (Solanum tuberosum L.), exhibits antioxidant activity in vitro.:J Agric Food Chem. 2003 Jul 16;51(15):4389-93Liu YW, Han CH, Lee MH, Hsu FL, Hou WC.School of Pharmacy, Taipei Medical University, Taipei 110, Taiwan, Republic of China.

 The potato (Solanum tuberosum L.) tuber storage protein, patatin, was purified to homogeneity with a molecular mass of 45 kDa. The purified patatin showed antioxidant or antiradical activity by a series of in vitro tests, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical (half-inhibition concentration, IC(50), was 0.582 mg/mL) scavenging activity assays, anti-human low-density lipoprotein peroxidation tests, and protections against hydroxyl radical-mediated DNA damages and peroxynitrite-mediated dihydrorhodamine 123 oxidations. Using electron paramagnetic resonance (EPR) spectrometry for hydroxyl radical detections, it was found that the intensities of the EPR signal were decreased by the increased amounts of patatin added (IC(50) was 0.775 mg/mL). Through modifications of patatin by iodoacetamide or N-bromosuccinimide, it was found that the antiradical activities of modified patatin against DPPH or hydroxyl radicals were decreased. It was suggested that cysteine and tryptophan residues in patatin might contribute to its antioxidant activities against radicals.


  Structural diversity and organization of three gene families for Kunitz-type enzyme inhibitors from potato tubers (Solanum tuberosum L.).:Mol Genet Genomics. 2003 Jul;269(4):526-34. Epub 2003 May 29.Heibges A, Glaczinski H, Ballvora A, Salamini F, Gebhardt C.Max-Planck-Institut f¨¹r Z¨¹chtungsforschung, Carl-von-Linn¨¦-Weg 10, 50829 K?ln, Germany.

 In the potato, Kunitz-type enzyme inhibitors are abundant and highly polymorphic small proteins found in tubers. DNA sequence analysis of 1596 unselected ESTs (expressed sequence tags) from mature tubers of the cultivars Provita and Saturna resulted in the identification of 55 different DNA sequences with high sequence similarity to Kunitz-type enzyme inhibitors. The frequency of Kunitz-type inhibitor ESTs in Provita was four times higher than in Saturna tubers, and none of the Provita ESTs was identical to any of the Saturna ESTs. A phenogram constructed from the deduced amino acid sequences of the inhibitors revealed three major homology groups-A, B and C. Group A inhibitors were all derived from Provita ESTs. Inhibitor groups A and B were more similar to each other than to group C inhibitors, and for most members within-group similarity was at least 90%. Non-conservative amino acid substitutions and insertion/deletion polymorphisms suggest functional differentiation between members of the gene family. A minimum of 21 genes for Kunitz-type enzyme inhibitors (six for group A, nine for group B and six for group C) was estimated to exist in the potato genome. Genetic mapping and the identification of BAC (bacterial artificial chromosome) clones containing more than one member of the gene family indicated that most inhibitor genes of groups A, B and C are organized in a cluster that maps to a single region on potato chromosome III.

  Determination of the starch-phosphorylating enzyme activity in plant extracts.:Planta. 2003 Mar;216(5):798-801. Epub 2002 Nov 9.Ritte G, Steup M, Kossmann J, Lloyd JR.Plant Physiology, Institute of Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25 Haus 20, 14476 Golm, Germany.

 For quantification of alpha-glucan, water dikinase (GWD) activity in crude extracts of plant tissues a radio-labeling assay was established that uses soluble starch and (33)P-labeled ATP as phosphate acceptor and donor, respectively. A constant rate of starch labeling was observed only if the ATP applied was labeled at the beta position. In wild-type extracts from leaves of Arabidopsis thaliana (L.) Heynh. the maximum rate of starch phosphorylation was approximately 27 pmol min(-1) (mg protein)(-1). Leaf extracts from the GWD-deficient sex1 mutants of Arabidopsis showed no significant incorporation of phosphate whereas extracts from potato (Solanum tuberosum L.) tuber expressing a GWD antisense construct exhibited less activity than the wild-type control. To our knowledge this is the first time that a quantification of the starch-phosphorylating activity has been achieved in plant crude extracts.

  Isolation and functional characterization of a stolon specific promoter from potato (Solanum tuberosum L.).:Gene. 2003 Jan 16;303:77-87.Trindade LM, Horvath B, Bachem C, Jacobsen E, Visser RG.Laboratory of Plant Breeding, Department of Plant Sciences, Graduate School Experimental Plant Sciences, Wageningen University, P.O. Box 386, The Netherlands. luisa.trindade@wur.nl

 In the search for time- and tissue-specific promoters an RNA fingerprinting technique called cDNA-AFLP was used. A transcript derived fragment (TDF511) was isolated which showed high similarity to alcohol dehydrogenases. The gene corresponding to this TDF, named Stgan, is likely to be involved in biosynthesis or breakdown of compounds affecting gibberellic acid (GA) levels in the plant [Plant J. 25(6) (2001) 595]. In this article the isolation and characterization of a Stgan promoter region is reported. The promoter region of this gene was fused to a reporter gene encoding beta-glucuronidase (GUS) and introduced in potato plants. GUS staining was detected uniquely in stolon tips and nodes. RNA in situ hybridization experiments revealed that this gene was specifically expressed in parenchyma cells, in the stolon cortex. Comparison of this promoter sequence with several promoter databases resulted in the identification of several potential binding sites for transcription factors. From the in vitro-culture experiments Stgan transcription appears to be induced by long days, sucrose and different hormones such as gibberellic acid, ancymidol, ethylene and cytokinins.

  Carotenoids and carotenoid esters in potatoes (Solanum tuberosum L.): new insights into an ancient vegetable.:J Agric Food Chem. 2002 Nov 20;50(24):7175-81.Breithaupt DE, Bamedi A.Institut f¨¹r Lebensmittelchemie, Universit?t Hohenheim, Garbenstrasse 28, D-70593 Stuttgart, Germany. breithau@uni-hohenheim.de

 The carotenoid pattern of four yellow- and four white-fleshed potato cultivars (Solanum tuberosum L.), common on the German market, was investigated using HPLC and LC(APCI)-MS for identification and quantification of carotenoids. In each case, the carotenoid pattern was dominated by violaxanthin, antheraxanthin, lutein, and zeaxanthin, which were present in different ratios, whereas neoxanthin, beta-cryptoxanthin, and beta,beta-carotene generally are only minor constituents. In contrast to literature data, antheraxanthin was found to be the only carotenoid epoxide present in native extracts. The total concentration of the four main carotenoids reached 175 microg/100 g, whereas the sum of carotenoid esters accounted for 41-131 microg/100 g. Therefore, carotenoid esters are regarded as quantitatively significant compounds in potatoes. For LC(APCI)-MS analyses of carotenoid esters, a two-stage cleanup procedure was developed, involving column chromatography on silica gel and enzymatic cleavage of residual triacylglycerides by lipases. This facilitated the direct identification of several potato carotenoid esters without previous isolation of the compounds. Although the unequivocal identification of all parent carotenoids was not possible, the cleanup procedure proved to be highly efficient for LC(APCI)-MS analyses of very low amounts of carotenoid esters.

  The effect of exogenous sugars on the control of flux by adenosine 5'-diphosphoglucose pyrophosphorylase in potato tuber discs.:Planta. 2002 Mar;214(5):741-50. Epub 2001 Oct 20.Sweetlove LJ, Tomlinson KL, Hill SA.Department of Plant Sciences, University of Oxford, South Parks Road, Oxford, OX1 3RB, UK.

 The aim of this work was to investigate the effect of exogenous sugars on the extent to which starch synthesis in potato ( Solanum tuberosum L.) is controlled by adenosine 5'-diphosphoglucose pyrophosphorylase (EC 2.7.7.27; AGPase). Tuber discs were incubated in the presence of a range of concentrations of glucose and sucrose, and metabolic fluxes measured following the supply of [U-14C]glucose and measurement of the specific radioactivity of the hexose phosphate pool. In the presence of glucose there was a marked increase in the flux through glucose-phosphorylating hexokinase, and at high concentrations of external glucose this led to a stimulation of the rate of starch and sucrose synthesis relative to those measured in the presence of sucrose. In the presence of glucose the ratio of the rate of starch synthesis to the rate of glycolysis was higher than in the presence of sucrose. Similar effects of glucose were observed at two stages of tuber development. We conclude that the presence of glucose perturbs the carbohydrate metabolism of tuber discs so that starch synthesis is favoured. In order to determine the extent to which AGPase controls flux, we measured fluxes in wild-type plants and transgenic plants with reduced AGPase activity as a result of the expression of a cDNA encoding the B subunit in the antisense orientation. In the presence of sucrose a reduction in AGPase activity had a greater impact on the rate of starch synthesis than in the presence of glucose. The flux control coefficient of AGPase over starch synthesis was higher in the presence of sucrose (0.7-0.9) than in the presence of glucose (0.4-0.6). Conversely, the impact of reduced AGPase activity on the rate of sucrose synthesis was lower in the presence of sucrose than glucose. In the presence of 200 mM sucrose the flux control coefficient of AGPase over the rate of sucrose synthesis was not significantly different from zero. This demonstrates that the nature of the sugar supplied to potato tuber discs can have a major influence on the distribution of control within metabolism. These data were also used to investigate the relationship between demand for ATP and the rate of hexose phosphate entry into glycolysis. A very strong correlation between ATP demand and glycolytic flux was demonstrated.


  Analysis of the compartmentation of glycolytic intermediates, nucleotides, sugars, organic acids, amino acids, and sugar alcohols in potato tubers using a nonaqueous fractionation method.:Plant Physiol. 2001 Oct;127(2):685-700.Farr¨¦ EM, Tiessen A, Roessner U, Geigenberger P, Trethewey RN, Willmitzer L.Max-Planck-Institut f¨¹r Molekulare Pflanzenphysiologie, Am M¨¹hlenberg 1, 14476 Golm, Germany. farre@mpimp-golm.mpg.de

 The compartmentation of metabolism in heterotrophic plant tissues is poorly understood due to the lack of data on metabolite distributions and fluxes between subcellular organelles. The main reason for this is the lack of suitable experimental methods with which intracellular metabolism can be measured. Here, we describe a nonaqueous fractionation method that allows the subcellular distributions of metabolites in developing potato (Solanum tuberosum L. cv Desiree) tubers to be calculated. In addition, we have coupled this fractionation method to a recently described gas chromatography-mass spectrometry procedure that allows the measurement of a wide range of small metabolites. To calculate the subcellular metabolite concentrations, we have analyzed organelle volumes in growing potato tubers using electron microscopy. The relative volume distributions in tubers are very similar to the ones for source leaves. More than 60% of most sugars, sugar alcohols, organic acids, and amino acids were found in the vacuole, although the concentrations of these metabolites is often higher in the cytosol. Significant amounts of the substrates for starch biosynthesis, hexose phosphates, and ATP were found in the plastid. However, pyrophosphate was located almost exclusively in the cytosol. Calculation of the mass action ratios of sucrose synthase, UDP-glucose pyrophosphorylase, phosphoglucosisomerase, and phosphoglucomutase indicate that these enzymes are close to equilibrium in developing potato tubers. However, due to the low plastidic pyrophosphate concentration, the reaction catalyzed by ADP-glucose pyrophosphorylase was estimated to be far removed from equilibrium.

  Identification and quantification of catecholamines in potato plants (Solanum tuberosum) by GC-MS.:Phytochemistry. 2001 Sep;58(2):315-20. Szopa J, Wilczy¨½ski G, Fiehn O, Wenczel A, Willmitzer L.Institute of Biochemistry and Molecular Biology, University of Wroclaw, Przybyszewskiego 63, 51-148, Wroclaw, Poland. szopa@biochem.microb.uni.wroc.pl

 Dopamine, norepinephrine, and normetanephrine were identified by GC-MS in potato (Solanum tuberosum L.) plants, the latter was new for plants. The highest amount of catecholamines was found in leaves. A developmental stage dependent variation in potato leaf catecholamines accumulation was also observed with highest level in third leaves. Catecholamine contents decrease during cold storage of tubers to undetectable levels. Mechanical wounding of leaves led to a small increase in the level of catecholamines investigated.

  Purification and characterization of an aspartic protease from potato leaves.:Physiol Plant. 2001 Jul;112(3):321-326.Guevara MG, Daleo GR, Oliva CR.Instituto de Investigaciones Biol¨®gicas (IIB), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata, CC 1245, 7600 Mar del Plata, Argentina.

 A protease was isolated from potato (Solanum tuberosum L. cv. Pampeana) leaves 48 h after detaching, when aspartic protease (AP) activity is markedly increased. Purification was performed by ammonium sulfate precipitation, ion exchange chromatography and affinity chromatography. A size of 40 kDa was estimated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis; it is monomeric and its properties are consistent with those of aspartic proteinases (EC 3.4.23): it has a pH optimum of 3 and it is inhibited by pepstatin. Like other plant APs, leaf AP appears to be glycosylated with a complex-type N-glycan. The enzyme has properties different from those of a tuber AP previously described, indicating that they may have different physiological roles.

  Comparison of hydroxyethyl starch solutions derived from potato and corn starch.:Anasthesiol Intensivmed Notfallmed Schmerzther. 2000 Dec;35(12):750-5. German.Rauch S, Sefrin P.Klinik f¨¹r An?sthesiologie, Universit?t W¨¹rzburg.

 OBJECTIVE: The study was designed to investigate the effects of hydroxyethyl starch (HES) solutions derived from potato (p) compared to HES derived from corn (c) starch on the colloidosmotic pressure, plasma viscosity, and to measure the plasma and urine concentration. METHODS: After approval by the Ethics Committee, and having obtained informed consent, we recruited 20 patients undergoing lumbar disc surgery who received either 1000 ml of p-HES or c-HES (MW 200,000 DS 0.5) in a randomized, single-blind way. Colloidosmotic pressure, plasma viscosity and the plasma concentration were measured before and 30, 90, 240 min and one day after the infusion. Statistical analysis was performed using chi-square and Mann-Whitney test. There were no differences between the two groups in regard to demographics and anesthesia. RESULTS: Plasma viscosity and colloidosmotic pressure did not change significantly during that time. There were no differences in plasma concentration and excretion of both solutions. The peak plasma concentration was reached after 30 min in both groups (8.57 +/- 3.92 g/l c-group and 7.67 +/- 4.68 g/l p-group) and declined thereafter. Within 6 h 38% (c-group 23.0 +/- 3.2 g HES) and 28% (p-group 16.8 +/- 1.6 g HES) of the infused HES were found in the urine. 12 h later about 50% was excreted. CONCLUSION: The present study demonstrated that there was no clinically apparent effect on hematorheology and pharmacokinetics between these two solutions.

  Molecular characterization of a novel glucose-6-phosphate dehydrogenase from potato (Solanum tuberosum L.).:Plant J. 2000 Sep;23(6):723-33. Wendt UK, Wenderoth I, Tegeler A, Von Schaewen A.Pflanzenphysiologie, FB5 Biologie/Chemie, Universit?t Osnabr¨¹ck, Barbarastrasse 11, 49076 Osnabr¨¹ck, Germany.

 We describe a novel G6PD cDNA from potato. The deduced amino acid sequence shares 77% identity with the known chloroplast enzyme, but only 47% with the corresponding cytosolic G6PDH. The sequence comprises the two cysteine residues conserved in other redox-regulated chloroplast G6PDH and a transit peptide capable of directing a GFP fusion protein to chloroplasts, demonstrating that the cDNA codes for a second plastidic G6PD isoform. The mature part was expressed in E. coli. When synthesized with a C-terminal Strep tag, the enzyme retained G6PDH activity upon affinity purification. In the presence of reductively activated spinach thioredoxin, G6PDH activity decreased by about 50%. This protein-mediated activity loss was completely reversed by addition of oxidant. In contrast to the chloroplast enzyme (P1), the presence of reduced dithiothreitol alone destroyed the activity of the new G6PDH (P2), and incubation with GSH had no effect. The Km values determined for both substrates were significantly lower compared to those of P1. The high Vmax and Ki [NADPH] values indicate that the P2 enzyme is more active than P1 and less susceptible to feedback inhibition by its product NADPH. At the level of mRNA accumulation, differences between the two plastid-localized isoforms are most prominent in roots and growing tissues. Immunoblot analyses of isolated plastid preparations revealed that the two plastidic enzymes are present in both root and leaf tissue. The data obtained indicate that we have characterized a second plastidic G6PDH with distinct biochemical features.


  Influence of storage upon light-induced chlorogenic acid accumulation in potato tubers (Solanum tuberosum L.).:J Agric Food Chem. 2000 Jun;48(6):2476-82.Percival GC, Baird L.Department of Plant Biology, Scottish Agricultural College, Auchincruive, United Kingdom. G.Percival@au.sac.ac.uk

 The influence of 2 weeks and 3 months of dark storage upon light-induced chlorogenic acid accumulation within tuber tissue of four potato cultivars and upon 5-, 4-, and 3-caffeoylquinic acid concentrations within cv. King Edward was determined. Storage period significantly affected (P < 0.05) the magnitude of the light-induced chlorogenic acid response with accumulation rates 3-4 times higher in tubers exposed to light after 2 weeks compared with those placed under light after 3 months. Comparison of chlorogenic acid concentrations in controls after 2 and 3 months of dark storage indicated that tuber chlorogenic concentrations decline during prolonged cold store at 5 degrees C. Rates of accumulation in response to light were cultivar-dependent with cv. Fianna the most light-sensitive and cv. Maris Piper relatively light-insensitive. In virtually all cases exposure to sodium and fluorescent light promoted higher rates of accumulation than did exposure to high-pressure mercury light sources. Chlorogenic acid values steadily increased over 15 days of illumination with, in the majority of cases, no indication of cessation. Light exposure increased 5-, 4-, and 3-caffeoylquinic acid accumulation rates in cv. King Edward. Irrespective of storage period and light source, ratios of 5-:4-:3-caffeoylquinic acid were ca. 85:15:0 at day 0 and 52:42:6 by day 15.

  Antimicrobial effects of Finnish plant extracts containing flavonoids and other phenolic compounds.:Int J Food Microbiol. 2000 May 25;56(1):3-12.Rauha JP, Remes S, Heinonen M, Hopia A, K?hk?nen M, Kujala T, Pihlaja K, Vuorela H, Vuorela P.Department of Pharmacy, University of Helsinki, Finland.

 Plant phenolics, especially dietary flavonoids, are currently of growing interest owing to their supposed functional properties in promoting human health. Antimicrobial screening of 13 phenolic substances and 29 extracts prepared from Finnish plant materials against selected microbes was conducted in this study. The tests were carried out using diffusion methods with four to nine microbial species (Aspergillus niger, Bacillus subtilis, Candida albicans, Escherichia coli, Micrococcus luteus, Pseudomonas aeruginosa, Saccharomyces cerevisiae, Staphylococcus aureus and Staphylococcus epidermidis). Flavone, quercetin and naringenin were effective in inhibiting the growth of the organisms. The most active plant extracts were purple loosestrife (Lythrum salicaria L.) against Candida albicans, meadowsweet (Filipendula ulmaria (L.) Maxim.), willow herb (Epilobium angustifolium L.), cloudberry (Rubus chamaemorus L.) and raspberry (Rubus idaeus L.) against bacteria, and white birch (Betula pubescens Ehrh.), pine (Pinus sylvestris L.) and potato (Solanum tuberosum. L.) against gram-positive Staphylococcus aureus.

  Kinetic mechanisms of linoleic acid oxidation by 5-lipoxygenase from Solanum tuberosum L.:Ukr Biokhim Zh. 1999 Jul-Aug;71(4):40-4. Ukrainian.Kharchenko OV, Kulinichenko HI, Butovych IA.Institute of Bioorganic Chemistry and Petrochemistry of National Academy of Sciences of Ukraine, Kyiv.

 Linoleic acid oxidation by 5-lipoxygenase from Solanum tuberosum has been studied as affected by sodium dodecylsulfate (Ds-Na). The reaction system consisted of 5-lipoxygenase and mixed micelles of linoleic acid and Lubrol PX. It contained varying amounts of the enzyme effector--Ds-Na. The enzyme showed a pronounced cooperativity, and the reaction was governed by the Hill equation with h = 3.7. On the other side, increasing amounts of Ds-Na added to the system caused a tremendous increase of enzyme activity and simultaneous decline of h, with was proportional to Ds-Na concentration. Ds-Na had dual effect on 5-lipoxygenase--there was an optimal concentration of the compound (0.34 mM Lubrol PX; 0.2 mM LA; 0.13 mM Ds-Na; pH = 6.3) causing the 4-fold highest activation and h = 1.6. The further increase of Ds-Na led to the enzyme inhibition. If Ds-Na was 0.5 mM, h became 1. At this point, each molecule of 5-lipoxygenase bound 3 molecules of Ds-Na and 1 molecule of linoleic acid, thus the total number of occupied binding sites was 4. A kinetic scheme of 5-lipoxygenase reaction has been proposed. It was found that the enzyme's kinetic behaviour could be explaine if assumed an existence of a special noncatalytic binding centre capable of binding several (up to 3) molecules of either substrate, or effector. Such a centre can serve as an anchoring site facilitating the enzyme binding to the surface of lipid aggregates containing insolubilized substrate molecules. Replacing linoleic acid in the binding site, Ds-Na activates the enzyme, possibly due to the much more effective translocation of 5-lipoxygenase to the surface of lipid aggregates. This mechanism can be an universal alternative to the FLAP-type regulation of 5-lipoxygenase activities.

  Isolation and partial characterization of thermostable isoperoxidases from potato (Solanum tuberosum L.) tuber sprouts.:J Agric Food Chem. 2000 Mar;48(3):701-7.Boucoiran CF, Kijne JW, Recourt K.Department of Agrofibres and Cellulose, Agrotechnological Research Institute (ATO-DLO), P.O. Box 17, 6700 AA Wageningen, The Netherlands. c.f.s.boucoiran@plant.wag-ur.nl

 Peroxidases (POD; EC 1.11.1.7) can cross-link cell wall polymers and may have an impact on the final textural quality of potato tubers. Because heat treatments are important during processing, the thermal properties of isoPODs from soluble and ionically and covalently bound fractions were studied from both potato tubers and sprouts. For both tissues, the ionically bound fraction was the most thermostable; approximately 20% of POD activity remained after a heat treatment of 10 min at 90 degrees C (for sprouts). The temperature profile of the ionically bound sprout fraction appeared to be nonlinear and suggested the presence of a very thermostable POD, which still showed activity after a heat treatment at 100 degrees C. Visualization by using isoelectric focusing confirmed the occurrence of a thermostable isoPOD with an IEP of 9.5, which displayed regeneration of activity after heat inactivation. This cationic POD was further purified by chromatography techniques, and by SDS-PAGE its molecular mass was estimated at 38 kDa.

  Effect of an algae extract and several plant growth regulators on the nutritional value of potato (Solanum tuberosum L. var. gigant).:Arch Latinoam Nutr. 1999 Jun;49(2):166-70. Spanish.Mart¨ªnez Lozano S, Verde Star J, Maiti RK, Oranday A, Gaona H, Aranda E, Rojas M.Universidad Aut¨®noma de Nuevo Le¨®n e Instituto Tecnol¨®gico, Nuevo Le¨®n, M¨¦xico.

 Four commercial plant-growth (Biofol, Biozyme, Cytokin and Activol) and an extract from algae (AlgaEnzims) were applied at commercial doses in potatoes (S. tuberosum L. var. gigant) with and objective to evaluate its effect on nutritional value (dry-matter, water content, ashes, fat, protein, carbohydrates and assimilable fiber). These parameters were analyzed according to the Official Methods of Analysis (AOAC). The experimental design was in Random Blocks with 8 treatments and 4 replications with 32 lots in total. The statistical analysis was after Random Blocks for all bromatological analyses. The treatment algae in soil gave the highest ash content (6.20). Algae in soil (9.30), algae on foliage (8.90) and Cytokin (8.70) gave the highest values in protein as compared with test (6.20). Carbohydrate content was highest in Biofol (88.21), assimilable fiber was higher in algae in soil and on foliage (5.84) and lowest with Biofol (1.67). Highest fat content in the tuber was obtained with Biozyme and Cytokin and highest protein content with AlgaEnzims. With Activol the highest tuber production is obtained.


  Scientific References:

  1.Research Update:Potato or Solanum tuberosum L.