Studies on chlorogenic acid biosynthesis in sweet potato root tissue using trans-cinnamic acid-2-14C and quinic acid-G-3H

When either trans-cinnamic acid-2-¹⁴C or quinic acid-G-³H wasadministered to sweet potato root discs, each compound was incorporatedinto chlorogenic acid. Hydrolysis analysis revealed that trans-cinnamicacid-2-¹⁴C and quinic acid-G-³H were selectively incorporatedinto the aromatic and non-aromatic moieties of chlorogenic acid,respectively. Quinic acid-G-³H was considered a more efficient precursor thantrans-cinnamic acid-2-¹⁴C, based on data of dilution values,incorporation percents and pool sizes in the tissue. No conjugatesof trans-cinnamic acid and quinic acid were detected in discsadministered trans-cinnamic acid-2-¹⁴C or quinic acid-G-³H.From these experimental results, a possible biosynthetic pathwayfor chlorogenic acid has been proposed. ¹ This paper constitutes Part 98 of the Phytopathological Chemistryof Sweet Potato with Black Rot or Injury. (Received November 2, 1971; )     

Effects of the Temperature of the Rooting Zone on the Growth and Development of Roots of Potato (Solanum tuberosum)

In solution culture the effect of optimal (20 °C) and supra-optimal(30 °C) root-zone temperatures on root growth and root morphologyof six potato clones (Solanum tuberosum L spp) was studied Growthwas compared with sweet potato (Ipomoea batatas L) and cassava(Manihot esculenta Crantz) Significant genotypical differencesin the responses of potato roots to supra-optimal temperatureswere observed, indicating the potential for selecting heat tolerantpotato clones In both heat tolerant and heat sensitive clones,the size of the root system was reduced by supra-optimal root-zonetemperature This was principally a result of decreased numberand length of lateral roots The first symptom of heat damagewas a reduction in the rate of cell division, followed by cessationof root elongation Bending of the apical root-zone togetherwith the formation of root hairs on the inner (concave) andlateral roots on the outer (convex) side were other symptoms,these coincided with the loss of starch granules in the root-cap Potato, genotypical differences, root morphology, root growth, temperature, Solanum tuberosum L     

The possible involvement of a spore agglutinating factor(s) in various plants in establishing host specificity by various strains of black rot fungus, Ceratocystis fimbriata

Extracts, possibly containing a factor(s) which agglutinatesspores of Ceratocystis fimbriata, were obtained from the sweetpotato, potato, taro, cucumber and kidney bean. The factor(s)seemed to be involved in the expression of host specificityby various strains of C. fimbriata. The agglutinating factor(s)from sweet potato root had a high molecular weight and was inactivatedby pronase or macerozyme treatment. (Received March 6, 1974; )     

Isolation of 1-O-trans-p-Coumaroyl-r{beta}-D-glucopyranose from Sweet Potato Roots and Examination of Its Role in Chlorogenic Acid Biosynthesis

1-O-trans-p-Coumaroyl-rß-D-glucopyranose (p-coumaroyl-D-glucose)was isolated from slices of sweet potato root which had beenincubated with trans-cinnamic acid. Pre-loaded trans-cinnamicacid efficiently trapped the radioactivity from L-[U-¹⁴C]-phenylalanineand reduced its incorporation into chlorogenic acid by 75% ofcontrol values in disks of sweet potato root. In the root diskssupplied with trans-[3-¹⁴C]-cinnamic acid, the radioactivitywas transferred first to trans-cinnamoyl- D-glucose, then top-coumaroyl-D-glucose, and subsequently to chlorogenic acidand isochlorogenic acid. These results support our earlier propositionthat p-coumaroyl-D-glucose is involved in the biosynthesis ofchlorogenic acid as an intermediate adjacent in the pathwayto trans-cinnamoyl-D-glucose in sweet potato roots. (Received April 11, 1988; Accepted August 9, 1988)     

CHANGE OF B-TYPE HAEM CONTENT IN RELATION TO PEROXIDASE BIOSYNTHESIS IN INJURED SWEET POTATO ROOTS

The methods of quantitative analysis of b-type haem in plantswere investigated. With an improved method developed was determinedthe haem content in the supernatant, mitochondrial, and microsomalfractions of sweet potato tissue. The activities of peroxidase,catalase, and cytochrome oxidase, as well as the contents ofb-type haem and acid-insoluble nitrogen in the cellular fractionswere determined at different incubation times after cuttingof sweet potato tissue. Peroxidase and catalase increased withtime in each celluler fraction, following a short lag phase.In the mitochondrial fraction, b-type haem, cytochrome oxidase,and acid insoluble nitrogen increased linearly with time. Inthe microsomal and supernatant fraction, b-type haem increasedwith time following a short lag phase. The increase in haemcontent of the supernatant fraction appeared to be associatedwith peroxidase formation. Time course analysis showed that ⁵⁹Fe-incorporation into b-typehaem of the supernatant fraction increased with time and thatincorporation was markedly inhibited by blasticidin S. The incorporationof ⁵⁹Fe into mitochondrial haem did not increase with time andwas not inhibited by blasticidin S. Blasticidin S inhibited⁵⁹Fe-incorporation into microsomal haem. Time course analysisof b-type haem content, ⁵⁹Fe-incorporation into b-type haem,and peroxidase activity suggest that in the injured tissue haemis synthesized from low molecular weight compounds and is incorporatedinto peroxidase as the haem moiety. ¹ This paper constitutes Part 57 of the Phytopathological Chemistryof Sweet Potato with Black Rot. ² Present address: Institute for Plant Virus Research, Chiba.     

Enhancement of Tuberization of Axillary Shoot Buds of Potato (Solarium tuberosum L.) Cultivars Cultured In Vitro

Factors controlling growth and tuberization of axillary budsin shoots of plantlets of potato (Solarium tuberosum L.) culturedin vitro were investigated. Correlative inhibition restrainedgrowth and tuberization of the axillary buds. Exposure of intactplantlets for various periods (4 to 48 h) to low (2 or 12C)or high (30 C) temperatures as comparedto 18C, did not alleviatecorrelative inhibition. Removal of the apical part of the shoot,the roots or both was generally ineffective Elevating sucroseconcentration from 30 to 80 g dm^–3 promoted tuberizationon axillary buds, and the cytokinin 6-(-dimethylallylamino)purine (2iP), alleviated correlative inhibition and enhancedtuberization in intact plantlets. In the whole plantlet mostof the tubers were formed on the basal nodes, however, oncecorrelative inhibition was eliminated by the dissection of theshoot to single node sections, tubers were formed on every axillarybud. The single most effective factor inducing tuberizationin single node sections was the growth retardant ancymidol,an inhibitor of giberellin biosynthesis. Key words: Potato, Solanum tuberosum L., in vitro tuberization, correlative inhibition     

Water Control and Survival of Ipomoea batatas Grown Photoautotrophically under Forced Ventilation and Photomixotrophically under Natural Ventilation

Water loss and its determining factors were compared in leavesof in vitro -grown sweet potato (Ipomoea batatas L. Lam, ‘Beniazuma’)plantlets cultured either photoautotrophically under forcedventilation (scaled-up vessel) or photomixotrophically undernatural ventilation. Functional stomata, a greater amount ofwax deposition on the leaves and smaller epidermal conductancewere observed in plantlets cultured photoautotrophically underforced ventilation. When transplanted directly into soil inthe greenhouse (without ex vitro hardening), plantlets grownphotoautotrophically under forced ventilation survived betterand grew faster. This was because they were better able to controltranspiration and thus lost less water and showed no signs ofwilting. In contrast, plantlets cultured under photomixotrophicconditions had open stomata which were not functional, a highertranspiration rate, and uncontrolled and rapid water loss immediatelyafter transfer ex vitro. Thus, wilting and severe desiccationwith irreversible tissue damage were observed in the leaves,which died within a few days. Copyright 2000 Annals of BotanyCompany Epicuticular wax, hardening, stomata, sweet potato, transpiration, water control     

Properties, development and cellular-localization of cinnamic acid 4-hydroxylase in cut-injured sweet potato

In sweet potato root tissue, cinnamic acid 4-hydroxylase activityincreased markedly in response to cut injury, and reached amaximum after 1 day of incubation. The patterns of developmentand successive decline were similar to those for phenylalanineammonia-lyase activity. The development of both enzyme activitieswas inhibited by cycloheximide. The activity was strictly dependenton pH of the homogenizing and reaction media. The optimum pHof the reaction was 8.0. The respective Km values for trans-cinnamicacid and NADPH were 2.6?10^-5 and 1.8?10^-6M. The activity wasnot affected by ß-mercaptoethanol and the intermediatesand product of the polyphenol biosynthetic pathway. Carbon monoxideinhibited strongly the activity and its inhibition was partiallyprevented by light. Thus, the enzyme may be involved in thecytochrome P-450 mediated electron transport system. Studiesusing differential centrifugation and sucrose density gradientcentrifugation, showed that the intracellular distribution of4-hydroxylase activity differed distinctly from that of themitochondrial marker enzyme and was not in accord with thatof NADPH-cytochrome c reductase activity. ¹This paper constitutes part 114 of the Phytopathological Chemistryof Sweet Potato with Black Rot and Injury. ²Present address: Laboratory of Biochemistry, Faculty of Agriculture,Nagoya University, Chikusa, Nagoya 464, Japan. (Received May 20, 1974; )     

Shoot Formation from Explant Cultures of Fourteen Potato Cultivars and Studies of the Cytology and Morphology of Regenerated Plants

Plants were regenerated in quantity from cultured excised stem,rachis or leaf pieces of 13 potato (Solarium tuberosum L.) cultivarsusing modifications of a two-step procedure. Pronounced differenceswere observed in the response of different cultivars and explantsources to medium formulations containing different auxins orcytokinins. A few plants were recovered from tuber pieces ofseven cultivars by a different two-step procedure. Morphologicaldifferences from control plants were observed in some of theprimary regenerants. Anthocyanin pigmentation of tubers wasscored and stable changes to red-splashed white or white tuberswere found in some plants regenerated from cv. Desiree. Regenerantsfrom the particoloured cultivars Cara and King Edward oftenlost this trait but it returned to varying extents in subsequentgenerations. Most of the regenerated plants (87 per cent) containedthe euploid number of chromosomes (2n = 4x = 48). The methodsare suitable for production of plants for assessment of somaclonalvariation in a range of genotypes. Potato breeding, somaclonal variation, chromosome variation, skin colour, explant culture, plant regeneration, solanum tuberosum L. potato     

Interrelation Between Growth Rate of Individual Potato (Solanum tuberosum L.) Tubers and Their Cell Number

In potato plants fast and slow growing tubers develop on thesame plant. A hypothetical causality between tuber growth rateand tuber cell number was investigated by determining the tubercell number with the aid of an automatic counting procedure.Our data show a close correlation between tuber size and cellnumber over the whole range of tuber volumes considered (3–28cm³). If the influence of tuber size on cell number is eliminatedby means of a partial correlation analysis, the cell numberof the entire tuber is not significantly correlated with itsgrowth rate. An exclusive consideration of the smaller cells(10–30 µm) in the apical tuber region, where thecell division rate in potato tubers is highest, reveals a loosebut significant partial correlation to tuber growth rate (r= 0.383, P < 0.05). The growth rate of the slow growing tubers of any potato plantmay be enhanced by removing the fast growing tubers. In thefirst few days this enhanced growth rate is not due to a stimulationof cell division rate, but rather due to cell expansion. Potato, Solanum tuberosum L., tuber growth rate, tuber cell number     

The Influence of Removing Tubers on Dry-matter Production and Net Assimilation Rate of Potato Plants

To study the effect of removing tubers on growth and net assimilationrate (E) of potato, plants were grown in pots partly filledwith soil with the shoot growing through a polythene cover.Tubers developed in the space between the cover and the soilsurface. Removing tubers immediately they began to form had little effecton E at the beginning of the experiment but later greatly reducedit. Shading reduced E more at the beginning of the experimentthan later. Removing tubers decreased total dry weight, butmuch of the material that would have moved to tubers accumulatedin leaves and stems. In intact plants the loss of weight byshading was mainly from the tubers; in plants without tubersit was mainly from stems and leaves. Removing tubers increasedleaves on lateral stems. Increasing the amount of nitrogen supplieddiminished the effect on E of removing tubers, presumably becausethe extra allowed other sinks for carbohydrate to develop. Thegrowth of some buds of the potato plant is so strongly inhibitedthat they cannot grow and act as sinks for excess carbohydratewhen tubers are removed. Such internal inhibition of growthmay sometimes suffice to influence the magnitude of E of normalplants. Removing tubers usually increased sugar and starch contentand protein N content of stems and leaves.     

Potato hexokinase 2 complements transgenic Arabidopsis plants deficient in hexokinase 1 but does not play a key role in tuber carbohydrate metabolism

Potato plants (Solanum tuberosum L. cv. Désirée) transformed with sense and antisense constructs of a cDNA encoding the potato hexokinase 2 exhibited altered enzyme activities and expression of hexokinase 2 mRNA. Measurements of the maximum catalytic activity of hexokinase revealed an 11-fold variation in leaf (from 48% of the wild-type activity in antisense transformants to 446% activity in sense transformants) and an 8-fold variation in developing tubers (from 35% of the wild-type activity in antisense transformants to 212% activity in sense transformants). Despite the wide range of hexokinase activities, no substantial change was found in the fresh weight yield, starch, sugar and metabolite levels of transgenic tubers. However, both potato hexokinases 1 and 2 were able to complement the hyposensitivity of antisense hexokinase 1 Arabidopsis transgenic plants to glucose. In an in vitro bioassay of seed germination in a medium with high glucose levels, double transformants showed the same sensitivity to glucose as that of the wild-type ecotype, displaying a stunted phenotype in hypocotyls, cotyledons and roots.     

Possible role of the cytosol pathway of acetyl-CoA supply in terpene biosynthesis in sweet potato infected with Ceratocystis fimbriata

Pyruvate was converted into acetyl-CoA by the cytosol enzymefraction prepared from sweet potato root tissue infected withCeratocystis fimbriata. The conversion was dependent on thiaminepyrophosphate, NAD⁺, ATP and CoA. Activities of pyruvate decarboxylase,aldehyde dehydrogenase and acetyl CoA synthetase increased indiseased tissue. These results indicate the operation of thecytosol pathway of acetyl-CoA supply for terpene biosynthesisin C. fimbriata-infected tissue which consists of the abovethree enzymes. ¹This paper constitutes Part 135 of the Phytopathological Chemistryof Sweet Potato with Black Rot and Injury. This work was supportedin part by a Grant-in-Aid from the Ministry of Education, Scienceand Culture. ²Present address: Biochemistry Department, University of Queensland,St. Lucia 4067, Queensland, Australia. (Received April 21, 1980; )     

Ageing of Cucumber and Onion Seeds: Phospholipase D, Lipoxygenase Activity and Changes in Phospholipid Content

Cucumber (Cucumis sativus L. cv. Mesa) and onion (Allium cepaL. cv. Rijnsburger Heldis) seeds were rapidly aged at 40 °Cand 74% relative humidity. Onion seeds were also slowly agedat 40 °C with 15% relative humidity for 11 months and onemore month at 28% relative humidity. Significant loss of totaland individual phospholipids was an early event during bothstorage treatments. With slow ageing of onion, loss of phosphatidylcholineoccurred several months before loss of viability and vigourwas detected. Phosphatidic acid, the lipid product of phospholipaseD action, increased during rapid ageing of both cucumber andonion. Phosphatidic acid was present in onion seeds before theageing treatments and its content remained unchanged in theslowly aged seeds. There was 1600 (cucumber) and 2000 (onion)times more phospholipase D activity (6 x 10⁵ and 2·9x 10⁵ nmol g^–1 d^–1 in cucumber and onion, respectively)in crude extracts from non-aged seeds than was required to accountfor the fastest fall in phospholipids (72, 372 and 144 nmolg^–1 d^–1 for cotyledons and radicles of cucumberand onion, respectively, over the first 9 d [cucumber] or 1d [onion] of ageing) and fastest increase in phosphatidic acid(7, 162 and 37 nmol g^–1 d^–1). How accurate a guidethe in vitro activity of phospholipase D was to the in vivoactivity was unclear. However, the considerable excess activityseen with the formation of phosphatidic acid supports the proposalthat hydrolysis of phospholipids by phospholipase D is a firststep in deterioration during ageing. Substantial lipoxygenaseactivity was also detected (58 x 10³ and 54 x 10³ nmol g^–1d^–1 respectively, for non-aged cucumber and onion seeds).However, the increase in conjugated dienes (an early productof peroxidation) in ageing cucumber seeds was comparativelysmall (90 nmol g^–1 d^–1 over 21 d ageing), and increasein malondialdehyde could not be detected, indicating that peroxidationmay not have been a major factor in cucumber. The increase inconjugated dienes during rapid ageing of onion seeds was larger(1·5 x 10³ nmol g^–1 d^–1 over days 0–2of rapid ageing), much greater than the decrease in phospholipidacyl groups (260 nmol g^–1 d^–1 over days 0–2of rapid ageing) indicating the occurrence of peroxidation offatty acids released from reserve as well as from membrane lipids.This higher level of conjugated dienes during onion ageing wasthe main difference between cucumber and onion, indicating thatthe level of peroxidation could be an important difference betweenfast and slow ageing seeds. However, peroxidation is not theonly possible deleterious process since hydrolysis of the normalmembrane phospholipids to phosphatidic acid increased the contentof non-bilayer-forming lipids and this too could be a directmembrane-destabilizing consequence of phospholipase D actionduring ageing. Key words: Cucumis sativus L. (cucumber), Allium cepa L. (onion), seed ageing, phospholipase D, lipoxygenase, phospholipids     

Initial Anatomical Changes Associated with Tuber Formation on Single-node Potato (Solanum tuberosum L.) Cuttings

One-node potato (Solanum tuberosum L. cv. ‘Katahdin’)cuttings were used to study early anatomical changes associatedwith tuberization. Starch deposition and the percentage frequencyof cells in mitosis increased in the medullary region of thebud within 1 d after cutting, whereas increases in average cellsize were not detected until 4 d after cutting. Starch depositionand mitosis were the earliest detectable changes in anatomyassociated with tuber initiation. Potato, Solanum tuberosum L., tuber initiation, cuttings, cell enlargement, mitosis, starch deposition     

Tuberization in Potato at High Temperatures: Interaction between Temperature and Irradiance

Potato plants (Solanum tuberosum L., cv. Sebago) responded similarlyto high temperatures and low irradiance by diverting dry matterto the shoots rather than the tubers, and changes were notedin a range of morphological characteristics. It is proposedthat the effect of both high temperature and low irradianceis brought about by the increased production of a growth substance,possibly gibberellin, which inhibits tuber formation, and thattuber yield is determined by the balance between temperatureand irradiance. Solanum tuberosum L., potato, tuberization, temperature, irradiance, gibberellin     

Changes in activity and isoenzymes of invertase in cucumber leaves due to nitrogen status

When 20 ppm ammonium nitrogen was supplied to nitrogen starvedcucumbers, acid and alkaline invertase activities increased6 and 2 fold on a fresh weight basis, respectively. Two acidinvertase isozymes, I and II, were detected in cucumber leavesby DEAE cellulose chromatography and Sephadex G-100 gel filtration.Their activities were found to be reversed in nitrogen-starvedand -sufficient cucumber leaves, isozyme II being the majorisozyme in nitrogen sufficient plant. Isozyme II had nearlyhalf the Km value of I for sucrose, and hydrolyzed raffinoseless than half as much as I did, although they showed the nearlysame pH optimum at 5.0 and similar heat stability. These resultsare discussed in relation to the regulatory role of acid invertasein cucumber leaves under different nitrogen status. (Received March 26, 1976; )     

Genetic Variation in Potato Cv. Record: Evidence from In Vitro 'Regeneration Ability'

Regeneration ability in vitro was studied in 170 individualtubers putatively derived from several or many parent plantsof the potato cv. Record. Of these, 120 were sprouted and thesprouts used to establish in vitro shoot cultures for leaf discproduction. The other 50 were grown in a glasshouse for theproduction of leaf discs. The reliable regeneration of somaclonesfrom leaf disc calluses was successful from only 11 parentaltubers. In ten of these, somaclones were derived from in vitroshoot cultures, and from a glasshouse-grown plant in the other.Four parental tubers gave the majority of somaclones, and one,R149, produced 85% of all somaclones at 15 months from initiationof leaf disc cultures. This differential regeneration abilitymay be due to genetic differences between tubers in this potatocultivar as it was found to be maintained in subsequent tubergenerations. The results are discussed in terms of seed potatoproduction and in vitro genetic conservation of vegetativelypropagated species. Potato, Solanum tuberosum cv. Record, regeneration ability, leaf disc culture, somaclonal variation     

The Induction and Development of Potato Microtubers In Vitroon Media Free of Growth Regulating Substances

Reliable microtuber production has been obtained by culturingnodal explants of potato on Murashige and Skoog medium withoutthe addition of growth regulating substances. The use of sucroseat 8 %, as compared with 4 or 12%, advanced the initiation oftuberization and gave more and larger microtubers. A periodof 1 month under 16 h days, followed by transfer to 8 h photoperiodsgave most rapid microtuber development. A reduction in the totalnitrogen supply or an increase in the ratio of ammonium to nitratereduced the size and number of microtubers Potato, Solanum tubersum L;, microtubers, in vitro induction and development, sucrose, photoperiod, nitrogen nutrition     

Effect of CO2 Concentration on Growth, Carbon Distribution and Loss of Carbon from the Roots of Maize

The effects of three ranges of CO₂ concentration on growth,carbon distribution and loss of carbon from the roots of maizegrown for 14 d and 28 d with shoots in constant specific activity¹⁴CO₂ are described. Increasing concentrations of CO₂ led toenhancement of plant growth with the relative growth rate (RGR)of the roots affected more than the RGR of the shoots. Between16% and 21% of total net fixed carbon (defined as ¹⁴C retainedin the plant plus ¹⁴C lost from the root) was lost from theroots at all CO₂ concentrations at all times but the amountsof carbon lost per unit weight of plant decreased with time.Possible mechanisms to account for these observations are discussed. Key words: Growth, Roots, Carbon loss, [CO₂]