Tuber-forming Substances in Jerusalem Artichoke (Helianthus tuberosus L.)

Four tuber-forming substances in Jerusalem artichoke were isolated from the leaves. The structures were established by spectroscopic methods as jasmonic acid (2), methyl β-D-glucopyranosyl tuberonate (3), and two new polyacetylene compounds, methyl β-D-glucopyranosyl helianthenate A (4, C₁₉H₂₄O₈) and B (5, C₁₇H₂₂O₈).     

UDP-glucose Pyrophosphorylase from Tubers of Jerusalem Artichoke (Helianthus tuberosus L.)

UDP-glucose pyrophosphorylase of Jerusalem artichoke tubers was purified 90-fold over the crude extract. The purified enzyme preparation absolutely required magnesium ions for activity. Cobalt ions were 60% as effective as magnesium ions; other divalent cations including manganese showed little or no effect. This enzyme had a pH optimum of 8.5 and a temperature optimum of 40°C. ATP and UDP inhibited the activity of this enzyme in both forward and backward directions. Km values for UDP-glucose, inorganic pyrophosphate, glucose-1-phosphate and UTP were determined to be 4.45 × 10^?4 M, 2.33 × 10^?4 M, 9.38 × 10^?4 M and 2.98 × 10^?4 M, respectively. These results are discussed in comparison with those of UDP-glucose pyrophosphorylases isolated from other plants.     

Phytochrome Control of Phenylalanine Ammonia-Lyase Levels and the Regulation of Cell Division in Artichoke Callus Cultures

Phytochrome controls phenylalanine ammonia-lyase (PAL) levelsin synchronously-dividing tuber tissue of the Jerusalem artichokeduring S but not during G₁. Red light enhances extractable PALlevels during S and the effect is far-red reversible. Howeverit is concluded that the effect of phytochrome on PAL levelsis only secondary since this effect is manifest many hours afterthe light treatments. Consequently, the relationship betweenphytochrome, PAL levels and cell division cannot be a simpleone.     

The Effect of L-Phenylalanine on Phenylalanine Ammonia-lyase and Cell Division in Artichoke Callus Culture

5 x 10^–5 M L-phenylalanine overcame the inhibitory effectof white light on cell division in artichoke callus culturesand increased extractable phenylalanine ammonia-lyase (PAL)activity compared to cultures grown in the presence of 5 x 10^–4M phenylalanine The lower concentration of the amino acid alsoenhanced rates of uptake and incorporation of ¹⁴C labelled phenylalaninethroughout G₁ and S. Differences between the two concentrationswere greatest during S with a 4-fold increase in uptake anda 3-fold increase in incorporation It is suggested thereforethat the capacity of 5 x10^–5 M phenylalanine to offsetthe light effect is due to an indirect stimulatory effect onamino acid and protein metabolism Increased levels of extractablePAL activity would then be reflected by this general stimulationof protein synthesis. Helianthus tuberosus L, Jerusalem artichoke, callus culture, cell division, phenylalanine ammonia-lyase     

The Isolation and Characterization of the Acid-Soluble Nucleotides from the Tubers of Jerusalem Artichoke (Helianthus tuberosus L.)

The acid-soluble nucleotides were extracted from the tubers of Jerusalem artichoke with percbloric acid, and separated and purified by means of adsorption on and elution from active charcoal, repeated chromatography on columns of Dowex I (Cl^-), followed by paper chromatography. The following nucleotides have been characterized and/or identified: 5′-AMP, 3′-AMP, ADP, ATP, 5′-GMP, 2′-GMP, 3′-GMP, 2′,3′-cyclic GMP, GDP, GTP, 5′-UMP, UDP, UTP, NADP, UDP-glucose, UDP-galactose, UDP-fructose, UDP-N-acetylhexosamine and GDP-mannose.^** Neither cytosine ribonucleotides nor deoxyribonucleotides have been detected. The significance of these observations is discussed.     

DNA Synthesis During the Early Division Cycles of Jerusalem Artichoke Callus Cultures

The pattern of DNA replication in relation to the first-divisioncycle of tissue cultures of explants from Jerusalem artichoketubers has been determined by Feulgen photometry of nuclei insections from a single experimental series. After a G₁ phaseof 25 h there is an ‘S’ phase of 14 h followed almostimmediately by mitosis which lasts for 2 h. These figures arecompared with estimated values for the same phases in the second-divisioncycle.     

Biochemical Properties of the Plasmalemma ATPase of Jerusalem Artichoke (Helianthus tuberosus L.) Tubers in Relation to Dormancy

Enzymological properties of the ATPase of plasmalemma-enrichedfractions obtained from the parenchyma of Jerusalem artichoke(Helianthus tuberosus L.) tubers were studied in relation tothe morphogenetic properties of the tubers. Preparations fromdormant tubers showed higher V_max and K_m values than those fromnon-dormant tubers. These differences persisted after solubilizationof the enzyme with octylglucoside, but were slightly modifiedafter addition of K$ to the reaction medium. The implicationsof these results are discussed in relation to the morphogeneticproperties of the tubers (Received August 24, 1987; Accepted March 19, 1988)     

Nuclear and Nucleolar Size Changes and Nuclear Pore Frequency in Cultured Explants of Jerusalem Artichoke Tubers (Helianthus tuberosus L.)

Nucleolar and nuclear envelope size changes in cultured explantsof H. tuberosus L. were studied prior to the first mitotic division.Using the technique of nuclear isolation to facilitate measurementsresults were obtained showing an almost immediate increase innuclear envelope surface area, while nucleolar volume showedno appreciable increase until 4 h after excision. The sharpincrease in nucleolar volume shown at this time reaches a maximumat 18 h which is maintained until mitosis occurs. The frequencyof nuclear pores remains constant. These results are discussedin the light of previous work on levels of RNA throughout theactivation process.     

Effects of Sequential Exposure to Auxin and Cytokinin on Xylogenesis in Cultured Explants of Jerusalem Artichoke (Helianthus tuberosus L.)

During the course of a 4-d culture period, explants of Jerusalemartichoke tuber were exposed to auxin (0.2 mg 1^–1 2, 4-dichlorophenoxyaceticacid), and cytokinin (5.0 mg 1^–1 benzyl-amino purine),under a range of sequential regimes, to study the influenceof each hormone on tracheary element formation. The resultsindicate that auxin was necessary early in the culture periodand was primarily involved in cell proliferation. Cytokininstimulated xylogenesis when present late in the culture period,concomitant with the phase of cytodifferentiation, but not whenrestricted to the early period. The implications for a sustainedperiod of commitment to differentiation are discussed. Xylem differentiation, Jerusalem artichoke, auxin, cytokinin, tissue culture     

Ultrastructural Changes in the Nucleoli of Jerusalem Artichoke (Helianthus tuberosus) Tuber Discs

Discs cut from Jerusalem artichoke (Helianthus tuberosus) tubertissue were shaken in distilled water at 25?C (termed ageing)for periods of 0, 3, and 24 h when samples were prepared forelectron microscopy. Tissue samples were fixed with 3 per centbuffered glutaraldehyde followed by osmium tetroxide. The ultrastructureof the nucleolus changes significantly with ageing. By 3 h aregion which we identify as nucleolar-organizing chromosomeis beginning to move from an external position on the nucleolusinto the fibrillar region. By 24 h this chromosomal region hasbecome dispersed as small areas within the fibrillar zone. Atthe same time the nucleolus develops a large granular zone.These changes are discussed with reference to the known increasein RNA synthesis during the ageing process.     

Evidence for the Cell Wall Involvement in Temporal Changes in Freezing Tolerance of Jerusalem Artichoke {Helianthus tuberosus L.) Tubers during Cold Acclimation

We studied the mechanism of cold acclimation of Jerusalem artichoke{Helianthus tuberosus L.) tubers with special reference to therole of the cell wall. During the cold-acclimation process fromSeptember to January, the freezing tolerance of tubers increasedfrom – 2.8°C to –8.4°C (LT₅₀). By contrast,the isolated protoplasts con- stitutively showed a consistenthigh level of freezing toler ance (LT₅₀; below – 25°C)throughout the period. In tuber tissues, freezing injury waseffectively protected by the ex ternal addition of isotonicsolutions. Cryomicroscopic ob servations revealed that tissuecells mounted in isotonic so lutions plasmolyzed upon freezing;tissue cells mounted in water collapsed with a tight attachmentof plasma mem brane to the cell wall. Upon freezing of intacttissues in water to temperatures below the critical range, thecyto plasm was irreversibly acidified as revealed by a fluorescence pH-ratiometry, suggesting that occurrence of detri mentalcellular events leading to permanent cell injury. The freeze-inducedacidification of cytoplasm was also effective ly prevented bythe external addition of isotonic solutions. These results suggestthat the tight attachment of the plas ma membrane to the cellwall during freezing may have a harmful effect on cells, inparticular on the plasma mem brane, possibly due to mechanicalor some sort of chemi cal/physico-chemical interaction withthe cell wall. ¹Contribution no. 3946 from The Institute of Low TemperatureScience, Hokkaido University. This research was supported inpart by the grant from Japan Society for the Promotion of Science(JSPS-RFTF 96L00602)²Present address: Tohoku National Agricultural Experiment Station, Morioka, Iwate, 020-01 Japan     

Vacuolar Membrane Lesions Induced by a Freeze-Thaw Cycle in Protoplasts Isolated from Deacclimated Tubers of Jerusalem Artichoke (Helianthus tuberosus L.)

The processes of freezing injury in Jerusalem artichoke (Helianthustuberosus L.) tubers were studied using protoplasts isolatedfrom cold-acclimated and deacclimated tubers. Prior to freezing,protoplasts were preloaded with 10 µM fluorescein diacetate(FDA) in an isotonic sorbitol solution. After freeze-thawingat various temperatures, cell viability was evaluated undera fluorescence microscope. In cold-acclimated tubers, more than80% of protoplasts survived freezing to – 20°C. Bycontrast, in deacclimated tubers, the cell survival abruptlydeclined after freezing to temperatures below – 5°C.Thus, freezing tolerance differed significantly between protoplastsisolated from cold-acclimated and deacclimated tubers. Two distincttypes of cell injury, which were caused by either damage toplasma membrane (cell-lysis type) or by damage to the vacuolarmembrane (abnormal-staining type), were observed, dependingon the cold hardiness and freezing temperature. In the cellsof the abnormal-staining type, shrinkage of the central vacuolarspace and simultaneous acidification of the cytoplasmic spacewere characteristically observed immediately before completecell-rehydra-tion during thawing. The decrease in freezing toleranceof protoplasts after deacclimation was suggested to be due mainlyto destabilization of the vacuolar membrane by freeze-induceddehydration stress. ¹Contribution no. 3945 from The Institute of Low TemperatureScience, Hokkaido University. This research was supported inpart by the grant from Japan Society for the Promotion of Science(JSPS-RFTF 96L00602) ²Present address: Tohoku National Agricultural Experiment Station, Morioka, Iwate, 020-01 Japan     

Some Possibilities for the cultivation and processing of Jerusalem artichoke (Helianthus tuberosus L.)

Investigations were carried out on the following; (i) the cultivation of Jerusalem artichoke: the advantages of J. artichoke as compared to other crops, (ii) advanced analytical procedures, such as HPLC, were used for the analyses of inulin synthesis and its hydrolytic breakdown and (III) ethanol production was focused on with respect to lower energy consumption with Kluyveromyces marxianus.     

Seawater Stress Differentially Affects Germination, Growth, Photosynthesis, and Ion Concentration in Genotypes of Jerusalem Artichoke (Helianthus tuberosus L.)

Two Jerusalem artichoke (Helianthus tuberosus L.) genotypes, NY-1 and NY-7, were subjected to different seawater concentrations (0, 10, 20, 30, 40, and 50%) for various periods of time to determine the effects on seedling growth, ion content, and photosynthetic productivity in a greenhouse. Under different seawater concentrations, sprouting rates varied greatly among the genotypes. The differences in relative growth rate (RGR), leaf chlorophyll content, total leaf area (TLA), plant dry weight (PDW), photosynthetic rate (A), stomatal conductance (g _s), and efficiency of the light harvesting of photosystem II (F _v^′/F _m^′) were significant between NY-1 and NY-7 after 12 days of stress at 40 and 50% seawater. Seawater treatments resulted in the reduction of almost all the growth parameters and coincident increases of Na⁺ and Ca²⁺ concentrations in plant tissues. Our results indicate that there is great variability for seawater tolerance among H. tuberosus varieties, and that greater photosynthesis capacity, higher RGR, and relatively higher tissue Na⁺ accumulation at high seawater concentrations appears to be associated with seawater tolerance in H. tuberosus varieties.     

Localization of the Enzymes of Fructan Metabolism in Vacuoles Isolated by a Mechanical Method from Tubers of Jerusalem Artichoke (Helianthus tuberosus L.)

Vacuoles isolated by a mechanical slicing method from developing tubers of Jerusalem artichoke (Helianthus tuberosus L.) contain activities of the two principal enzymes responsible for fructan synthesis: sucrose-sucrose fructosyl transferase and fructan-fructan fructosyl transferase. Both enzymes are associated with the vacuolar sap and not with the tonoplast. In vacuoles isolated from dormant tubers, the fructan-fructan fructosyl transferase activity remains in the vacuolar sap but the fructan exohydrolase activity is associated with the tonoplast. Fructan is hydrolysed by these vacuoles to fructose, which can be exported to the suspending medium. The localization of the enzymes of fructan metabolism in the vacuole has implications for the maintenance of fructan polymerisation.     

风沙地菊芋的主要生态学特性

菊芋(Helianthus tuberosus L.)根系发达,抗旱性强,具有重要的防风固沙功能.为了揭示菊芋防风固沙机理及生长适应性,对科尔沁沙地生长的菊芋主要生态学特性进行了研究.结果表明:菊芋的生长发育可分为出苗期、快速生长期和块茎膨大期3个时期;菊芋地上部器官生长与干物质积累8周之内增长缓慢,之后生长迅速,第18周块茎开始进入速生期,块茎干物质积累在第23周达到最大值,平均单株为298.15 g;菊芋的光合性能指标与干物质积累存在密切关系,其中菊芋叶面积指数、光合势均在地上部分生长速生期第9周起开始呈对数式增长,到地下块茎膨大速生期第18周达到最大值,分别为6.55、401016m2·d-1·hm-2;叶片叶绿素相对含量在地上干物质开始向块茎转移时最高,峰值为38.4.     

The Interaction between Exogenous NADH Oxidase and Succinate Oxidase in Jerusalem Artichoke (Helianthus tuberosus) Mitochondria

Most isolated plant mitochondria oxidize exogenous NADH viaan electron transport pathway which is resistant to piericidinA and coupled to the synthesis of two molecules of ATP. Resultspresented show that succinate can inhibit this oxidation ofadded NADH. The inhibition was most marked in the absence ofADP (state 4), less obvious in the presence of added ADP (state3), and absent in the presence of a weak acid uncoupling agent.The presence of malonate prevented the inhibition. The degreeof inhibition was dependent on the concentration of succinateand appeared to be non-competitive in nature. The inhibitionwas shown not to be the result of the reversed flow of electronsfrom succinate to NAD^$. The presence of external NADH appearednot to alter the rate of oxidation of succinate.     

Plasmalemma fluidity in parenchyma cells from Jerusalem artichoke (Helianthus tuberosus L.) tubers during the break of dormancy

Plasmalemma-enriched fractions were isolated from Jerusalem artichoke tubers along the time course of dormancy break produced by cold treatment. A decrease of membrane fluidity was noted from the 3^rd to the 8^th week of this treatment, as well as a decrease of plasmalemma NADH dehydrogenase activity from the 5^th to the 8^th week. The plasmalemma lipid extracts studied revealed two major phospholipidic components: phosphatidylcholine (PC) and phosphatidylethanolamine (PE). Their respective quantities decreased until the 12^th week, where the phosphatidylcholine level is lower than the phosphatidylethanolamine one. The observed changes are discused in relation to dormant and non-dormant states of tubers and the breaking of dormancy.     

RNA Accumulation in Relation to DNA and Protein Accumulation in Jerusalem Artichoke Callus Cultures

RNA accumulation during the synchronous early development ofJerusalem artichoke callus cultures follows a pattern of threestepwise increases in RNA per dividing cell during the firstdivision cycle. Little accumulation occurs in non-dividing cellsduring this time. These data are compared with data availablefor DNA replication, which occurs only in dividing cells, andfor protein accumulation which follows a similar pattern tothat of RNA accumulation in dividing cells, both in dividingcells and in some non-dividing cells.