Induction of the activity of glycolytic enzymes correlates with enhanced hydrolysis of sucrose in the cytosol of transgenic potato tubers

The aim of this work was to define the metabolic factors which regulate the respiratory pathways in trangenic potato tubers. We previously found that respiration is enhanced in transgenic tubers which express a yeast invertase and a glucokinase from Zymomonas mobilis . In this study we investigated glycolysis in three further transgenic potato lines with profound changes in the mobilization of sucrose. We studied antisense ADPglucose pyrophosphorylase lines which are characterized by a reduction in starch accumulation and a significant build up of sucrose and related metabolic intermediates. We also report the generation of two novel double transgenic lines where the yeast invertase is expressed specifically in tubers of the ADPglucose pyrophosphorylase antisense line, targeted to either the cytosol or apopolast. We evaluated whether the localization of sucrose cleavage had an impact on the glycolytic induction, and assessed if invertase expression in the high-sucrose background had any further effects on glycolysis. We found that induction of the glycolytic enzymes only occurs when the invertase is targeted to the cytosol, and that the extent of this induction was comparable in the wild type and antisenseADPglucose pyrophosphorylase backgrounds. We conclude that the signal regulating glycolysis is directly linked to cytosolic sucrose hydrolysis.     

Dibucaine,chlorpromazine, and detergents mediate membrane breakdown in potato tuber homogenates

Various strategies were evaluated for their ability to minimize the rate of breakdown of endogenous membrane lipids during cell fractionation studies with potato tubers. Buffering the homogenates at pH 7.5 to 8.0 resulted in significantly lower rates of phosphatidylcholine (PC) hydrolysis than were observed at lower pH values. Several potential inhibitors were added to homogenates to evaluate their ability to inhibit membrane lipid hydrolysis. The addition of bovine serum albumin (1% w/v) inhibited the rate of PC hydrolysis by 50%. The addition of low concentrations (25–100 μM) dibucaine (nupercaine) inhibited PC hydrolysis, but at higher concentrations (1-2 mM) it caused a 5- to 6-fold stimulation. Because dibucaine is a calmodulin antagonist, two other calmodulin antagonists (trifluoperazine and chlorpromazine) were tested and found to exhibit similar patterns of inhibition and stimulation. Similarly, the addition of low concentrations of deoxycholate also inhibited PC hydrolysis and high concentrations stimulated it. These results indicate that the hydrophobic properties of deoxycholate, dibucaine, and other calmodülin antagonists may explain their unusual effects on the rates of PC hydrolysis in potato tuber homogenates. Although the addition of exogenous calcium increased the rate of PC hydrolysis, the addition of calmodulin (bovine brain) had no effect. Other experiments revealed that the addition of 1% bovine serum albumin improved the yield and stability of mitochondrial and microsomal fractions from potato tubers. In constrast, the addition of 100 μM dibucaine caused deleterious effects.     

Potato water content impact on soil moisture measurement by neutron meter

A field study was conducted to examine the effect of the water content of potato tubers on the neutron count ratios of a neutron probe in an irrigated potato field. At the 20 cm depth, where tubers are concentrated, the neutron count ratios within the potato row (CW) were significantly higher than the neutron count ratios between the rows (CB). In contrast, the measured soil water contents within the rows (SW) at this depth, tended to be less than those measured between the rows (SB). At 45 cm depth, results were similar in a dry but not a wet year. The SW values, in contrast, were less than SB. Neither (CW-CB) or (SW-SB) were significant at 75 cm depth and values of (CW-CB) and (SW-SB) were similar. This study provides qualitative information regarding the influence of a potato tuber water content on neutron measurements, resulting in an overestimations of soil moisture in a potato field. Further studies should be conducted to develop relationships for corrections.Contribution no 3879215Contribution no 3879215     

Continuous production of fructose syrup and ethanol from hydrolysed Jerusalem artichoke juice

Summary The results from this study showed that Jerusalem artichoke juice can be used for the production of very enriched fructose syrup by selective conversion of glucose to ethanol in a continuous process using immobilized cells ofSaccharomyces cerevisiae ATCC 36859. The product contained up to 99% of the total carbohydrates as fructose compared to 76% in the feed. Using Jerusalem artichoke juice supplemented with some glucose a product was obtained with 7.5% w/v ethanol which made ethanol recovery economically favourable. It was found that some fructose was consumed in these continuous processes; the glucose/fructose conversion rate ratio was regulated by the glucose concentration in the product stream.     

Aroma volatiles of Cynara scolymus and Helianthus tuberosus

Samples of the aroma volatiles of globe artichoke and Jerusalem artichoke were obtained by well established methods and were analysed by routine GC and GC/MS. Eight sesquiterpene hydrocarbons afforded the major group of components (over 42%) in globe artichoke samples, with β-selinene (ca 32%) as the main constituent. Previously reported caryophyllene could not be detected. α-Cedrene was found to have globe artichoke aroma characteristics on odour evaluation of separated components at an odour port at the exit of the GC column. Jerusalem artichoke samples contained one major component (β-bisabolene, ca 51%) and a range of saturated long-chain hydrocarbons (ca 22%). The sesquiterpene presumably contributes appreciably to the characteristic flavour of Jerusalem artichoke. Both types of artichoke gave a low concentration of total volatiles.     

Enzyme inhibitors from plants: Enterokinase inhibitors in tubers and seeds

Of the 22 tubers and 9 pulses screened for inhibitors of enterokinase activity, the following 12 tubers,Curcuma amada, Kyllinga monocephala, Solanum tuberosum, Canna indica, Helianthus tuberosus, Coleus parviformis, Mirabilis jalapa, Colocasia antiquorum (red variety),Alium cepa, Amorphophalus companulatus, Maranta arundinacea, Daucus carota, and 9 pulses namely,Vigna sinensis, Arachis hypogea, Pisum sativum, Phaseolus vulgaris (white bean),Phaseolus vulgaris (kidney bean),Phaseolus mungo, Cicer arietinum, Dolichos lablab and Cajonus cajan contained inhibitory activity. Three tubers,Amorphophalus companulatus, Maranta arundinacea andDaucus carota and all the nine pulses exhibited endogenous esterase activity towards benzoyl arginine ethyl ester. Among the 8 pulses and 3 tubers processed by affinity chromatography on trypsin-sepharose, to separate trypsin inhibitor from enterokinase inhibitor,Phaseolus vulgaris (kidney bean),Phaseolus vulgaris (white bean) andDolichos lablab contained distinct enterokinase inhibitors. These fractions were devoid of trypsin inhibitor activity. The trypsin inhibitor fromColeus parviformis tubers alone did not bind to trypsinsepharose and was recovered in the unbound fraction along with the enterokinase inhibitor.     

Field evaluation of female sex pheromone of the artichoke moth, Gortyna xanthenes

Field responses of Gortyna xanthenes (Germar) males to traps baited with different mixtures of the female sex pheromone components were evaluated in an artichoke field. Catches were compared to those obtained by virgin females and light traps. The best results were achieved by utilizing a mixture of 5 mg Z11-16:Ald + 0.15 mg Z9-16:Ald + 0.15 mg 16:Ald + 0.12 mg Z11-16:OH, which captured only G. xanthenes males 3–5 times more than light traps and ca two times more than one virgin female. Starting from the basic mixture Z11-16:Ald (89–92%) + Z9-16:Ald (2–4%), the addition of 16:Ald (2–4%) and of Z11-16:OH (2–3%) produced an increase of G. xanthenes and a decrease of H, armigera (Hb.) catches. The inhibitory action of Z11-16:OH towards H. armigera males was confirmed.

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Evaluation sur le terrain des constituants de la phéromone sexuelle de la noctuelle de l'artichaut (Gortyna xanthenes)

Résumé Dans un champ d'artichaut de la province de Salerno on a evalué la réponse des mâles de G. xanthenes à mélanges divers des constituants de la phéromone sexuelle produite par la femelle. Les meilleurs résultats ont été obtenus en employant un mélange de 5 mg Z11-16:Ald + 0.15 mg Z9-16:Ald + 0.15 mg 16:Ald + 0.12 mg Z11-16:OH, qui a capturé seulement les mâles de G. xanthenes en mesure 3–5 fois plus élevée que les pièges lumineux et ca. deux fois plus élevée que la femelle vierge. En partant du mélange base Z11-16:Ald (89–92%) + Z9-16:Ald (2–4%), l'addition de 16:Ald (2–4%) et de Z11-16:OH (2–3%) a causé un accroissement des captures de G. xanthenes et une diminution des captures de Heliothis armigera. Cela confirme l'action inhibitoire du Z11-16:OH à l'égard des males de H. armigera.

     

Chemical Composition of the Tuber Essential Oil from Helianthus tuberosus L. (Asteraceae)

Helianthus tuberosus L. (Jerusalem artichoke) is cultivated in Europe and other parts of the world as a food crop and ornamental plant. The volatile oils of the aerial parts of H. tuberosus were investigated more than 30 years ago, but no study could be found to date on the constituents of the tuber essential oil. Herein, the first characterization by GC‐FID, GC/MS, and ¹³C‐NMR analyses of a hydrodistilled essential oil of Jerusalem artichoke tubers was reported. Fresh plant material collected in Serbia (Sample A) and a commercial sample (Sample B) yielded only small amounts of oil (0.0014 and 0.0021% (w/w), resp.). In total, 195 constituents were identified, representing 88.2 and 93.6% of the oil compositions for Samples A and B, respectively. The main constituents identified were β‐bisabolene ( 1 ; 22.9–30.5%), undecanal (0–12.7%), α‐pinene (7.6–0.8%), kauran‐16‐ol ( 2 ; 6.9–9.8%), 2‐pentylfuran (0.0–5.7%), and (E)‐tetradec‐2‐enal (0.0–4.9%). Several rare compounds characteristic for Helianthus ssp. were also detected: helianthol A ( 6 ; 2.1–1.9%), dihydroeuparin ( 10 ; 0.0–2.3%), euparin ( 9 ; 0.0–0.4%), desmethoxyencecalin ( 7 ; traces – 0.2%), desmethylencecalin ( 8 ; 0.0–0.4%), and an isomer of desmethylencecalin (0.0%‐traces). The essential oils isolated from the tuber and the aerial parts share the common major component 1 .