Sweet Potato Root Tissue Research Articles

Isolation of Possible Intermediate of Chlorogenic Acid Biosynthesis in Sweet Potato Root Tissue

Isolation of Possible Intermediate of Chlorogenic Acid Biosynthesis in Sweet Potato Root Tissue

Sucrose Synthetase of Sweet Potato Roots

The effect of concentration of each substrate in the reaction catalyzed by sucrose synthetase isolated from sweet potato roots was determined. For the sucrose synthesizing reaction, UDP-glucose(ADP-glucose)+fructose→sucrose+UDP(ADP), the substrate saturation curves for UDP-glucose, ADP-glucose and fructose were hyperbolic in shape and the reaction was strongly inhibited by UDP competitively. On the other hand, the substrates for the reversal of sucrose synthetase reaction, sucrose+UDP(ADP)→UDP-glucose(ADP-glucose)+fructose, exhibited a sigmoidal shaped saturation curve which was deviated from the Michaelis-Menten equation. The plot of data according to the empirical Hill equation gives a values greater than 1.0 for every substrate examined in the latter case. In view of these experimental data, the major role of sucrose synthetase is postulated in that this enzyme is involved in the breakdown of sucrose in sweet potato root tissues instead of the sucrose synthesizing reaction. The molecular weight of the ...

Structure of a new sesquiterpenoid, ipomeamaronol, in diseased sweet potato root tissue

Structure of a new sesquiterpenoid, ipomeamaronol, in diseased sweet potato root tissue

Modification of OGUR-ROSEN method for estimation of RNA in fresh and wounded sweet potato root tissues and change in RNA contents after the cutting<xref ref-type="fn" rid="fn1"><sup>1</sup></xref>

Modification of OGUR-ROSEN method for estimation of RNA in fresh and wounded sweet potato root tissues and change in RNA contents after the cutting<xref ref-type="fn" rid="fn1"><sup>1</sup></xref>

Induction of Peroxidase Activity by Ethylene in Sweet Potato

Metabolic activation in sweet potato root tissues injured by mechanical, chemical, or fungal damage has been extensively investigated. Previously, it was shown that metabolic activation, particularly peroxidase and phenylalanine-ammonia lyase activities, developed when sweet potato roots were sliced. These activities were significantly enhanced by a strikingly low level of ethylene exogenously supplied to the slices. Incubated root slices produced enough ethylene to enhance metabolic activation before any increase in enzyme activity occurred. It was also found that ethylene production is greatly stimulated when tissue is injured. A comparison of polyacrylamide gel electrophoretic patterns for peroxidase isoenzymes extracted from slices incubated with or without ethylene revealed identical qualitative patterns. Those results suggest that the metabolic activation which occurs in sliced tissues in the absence of exogenously added ethylene is regulated by endogenous ethylene produced in response to the injury caused by slicing the tissue. In the present communication, the author wishes to present additional evidence in support of the above view. Since the increase of peroxidase activity after slicing was particularly sensitive to exogenous ethylene, peroxidase activity is mainly dealt with in the present paper. 17 references.

Variation on Ethylene Production and Other Host Responses in the Tissues of Sweet Potato Infected by Some Strains of Ceratocystis fimbriata

Ethylene production in the infected sweet potato root or stem tissue by each strain of Ceratocystis fimbriata differing in pathogenicity (sweet potato strain, coffee strain or prune strain) was examined. Ethylene was remarkably produced in the tissue infected by sweet potato strain, whereas in the tissue infected by coffee strain a small amount of ethylene was produced, and in the tissue infected by prune strain the smallest amount was produced. The result corresponds with the fact which has been reported elsewhere that furano-terpenoids including ipomeamarone were produced most distinctly in infected tissue by sweet potato strain, while in infected tissue by coffee strain the amount produced was very small and in the infected tissue by prune strain the amount was the smallest. This indicated that ethylene as well as furano-terpenoids was produced in a larger amount in the infected tissue by the pathogenic strain. Since the production of ethylene corresponded well with fungus invasion and growth in the host tissue, it was regarded that the amount of ethylene produced in infected tissue might be an indicator to the degree of fungus multiplication.It was shown that when sweet potato root tissue (Norin 1, a moderate resistant variety, was used as a host) was inoculated with coffee or prune strain before infection by sweet potato strain, development of sweet potato strain in the host tissue was markedly suppressed The inhibitory effect was prominently observed in the tissue which had been previously infected by coffee strain. In fact, 50% inhibition (evaluated by ethylene production) was found by an hour prior inoculation with coffee strain to that with sweet potato strain. The mechanism of the inhibitory action caused by the pre-inoculation with a non-pathogenic strain upon multiplication of a pathogenic strain was discussed In connection with the above problem, it was also considered why a non-pathogenic strain ceased to penetrate the surface cells of the host tissue and could not develop further.

Enzymatic synthesis of isopentenyl pyrophosphate in sweet potato root tissue in response to infection by black rot fungus1

Enzymatic synthesis of isopentenyl pyrophosphate in sweet potato root tissue in response to infection by black rot fungus1

Effects of aflatoxins on metabolic changes in plant tissue in response to injury

Many kinds of metabolism have been demonstrated to be activated in slices of sweet potato root tissue during ageing. The effect of aflatoxin B 1 on the metabolic activation in this tissue in response to injury was investigated. Aflatoxin B 1 did not affect the synthesis of peroxidase, cytochrome oxidase and succinate dehydrogenase during ageing of sliced sweet potato root tissue. However, the toxin was found to inhibit the reproduction of mitochondria during ageing. Similar effects on the metabolic activation in the tissue were obtained with mitomycin c. It is concluded that aflatoxin B 1 inhibits the replication of deoxyribonucleic acid, without any effect on protein synthesis under the control of either nuclear or mitochondrial genes.

Production of Furano‐terpenoids and other Compounds in Sweet Potato Root Tissue in Response to Infection by various Isolates of Ceratocystis fimbriata

Production of Furano‐terpenoids and other Compounds in Sweet Potato Root Tissue in Response to Infection by various Isolates of <i>Ceratocystis fimbriata</i>

Some properties of shikimate: NADP oxidoreductase produced in sweet potato root tissue after slicing1

The activity of shikimate: NADP oxidoreductase [EC 1. 1. 1. 25] in sweet potato root tissue increased soon after slicing. Enzyme preparations obtained from both sliced tissue and from fresh tissue probably contained a single enzyme component, and they showed identical chromatographical behaviour. Km values of the enzyme for NADP and shikimate were 1.0×10−4M and 1.3 × 10−3M, respectively. Enzyme activity was potently inhibited by SH-inhibitors such as p-chloromercuribenzoate and oxidized glutathione. Enzyme activity was affected neither by mononucleotides such as ATP, ADP and AMP, divalent cations, Mg++, Ca++ and Mn++, nor by metabolites such as tryptophan, phenylalanine, tyrosine and t-cinnamic acid which are involved in aromatic compound syntheses. The enzyme rapidly lost its activity. This inactivation reaction showed a time course consisting of two steps of the first-order reaction. The inactivated enzyme preparation was not reactivated by thiol compounds such as cysteine, 2-mercaptoethanol and glutathione, although these reagents, to a certain extent, protected the enzyme from inactivation. The results suggest that denaturation of the enzyme protein was involved in inactivation of the enzyme.

Effect of antibiotics on biogenesis of mitochondria during aging of sliced sweet potato root tissue1

Effect of antibiotics on biogenesis of mitochondria during aging of sliced sweet potato root tissue<xref ref-type="fn" rid="fn1">¹</xref>

Biochemical Studies on the Terpene Metabolism in Sweet Potato Root Tissue with Black Rot

Using sweet potato root tissue infected with Ceratocystis fimbriata, the effect of farnesol, nerolidol or geraniol on the incorporation of acetate-2-14C into ipomeamarone and other lipids, and on the production of ipomeamarone and other lipids was examined. Acetate-2-14C incorpration into ipomeamarone and other lipids and the production of the lipids except ipomeamarone were markedly suppressed by the addition of the terpenol. The production of ipomeamrone was unaffected. It was concluded that the marked decrease of acetate incorporation into ipomeamarone in the presence of the terpenol was due mainly to the direct inhibition of the biosynthetic pathway and to a lesser extent to their dilution effect. The inhibitory sites by the terpenol seemed to be localized in at least 2 positions in the biosynthetic pathway of ipomeamarone. After feeding tissue disks with actetate-2-14C in the presence of farnesol or geraniol, either farnesol or geraniol was isolated, and the respective crystalline derivatives were fo...

Increase in the Dehydrogenase Activities of the Pentose Phosphate Pathway in Sweet Potato Root Tissue after Slicing

Glucose 6-phosphate and 6-phosphogluconate dehydrogenase activities of sliced sweet potato root tissue increased markedly during aerobic incubation at 30°C in a moist atmosphere. One band of glucose 6-phosphate and at least 3 bands of 6-phosphogluconate dehydrogenase were observed in the disc electrophoresis zymograms of the crude extracts. The marked differences were absent between fresh and sliced tissues. The intensity of the most rapidly migrating band of 6-phosphogluconate dehydrogenase seemed to increase in response to slicing.

The Incorporation of Leucine-U-14C into Ipomeamarone

1. It was demonstrated by silica gel thin layer chromatography that leucine-U-14C was incorporated into furanoterpenes, e. g. ipomeamarone, in sweet potato root tissue infected by Ceratocystis fimbriata.2. Further proof for ipomeamarone synthesis from leucine-U-14C was obtained by the constancy of the specific radioactivity of ipomeamarone semicarbazone through repetitive crystallization.3. The synthetic pathway of ipomeamarone from leucine was found to be connected with the synthetic pathway from acetate at least at some steps.4. Leucine-U-14C was incorporated into both saponifiable and non-saponifiable materials in the same way as acetate-2-14C.

Activation of Protein Synthesis and Biogenesis of Mitochondrial Particles during Aging of Discs of Sweet Potato Root Tissue

Protein synthesis in mitochondrial and supernatant fractions of sweet potato root tissue was found to be activated up to about 3 and 1.5 times in response to wounding, respectively. The activation seemed to take place within 8 hr after slicing. Sucrose density gradient centrifugation of mitochondrial fraction prepared from the aged sliced tissue showed the presence of new fraction of mitochondrial particles which were not seen in the case of fresh tissue. The particles in the fraction were labeled by radioactive leucine in vivo more rapidly than the other particles. Chloramphenicol treatment of tissue before aging blocked the development of these particles. These results suggest that the particles were newly formed during aging.

Participation of Mevalonate in the Biosynthetic Pathway of Ipomeamarone

The incorporation of mevalonate-2-14C into ipomeamarone in sweet potato root tissue infected by Ceratocystis fimbriata was demonstrated, but the rate was low when compared with acetate-2-14C. No dilution effect of mevalonate was noted during the incorporation of acetate-2-14C into ipomeamarone. This is very likely to result from the passive transfer of mevalonate into the cells.No dilution effect of acetate during the incorporation of mevalonate-2-14C into ipomeamarone was noted. This indicates that mevalonate is not incorporated into ipomeamarone after its conversion to acetate.Evidence for incorporation of acetate-2-14C into mevalonate was shown by the fact that the specific radioactivity of mevalonic acid benzhydrylamide was not lowered throughout repetitive crystallizations. These data also support the participation of mevalonate in ipomeamarone synthesis as an intermediate.

Production of ethylene by injured sweet potato root tissue&lt;xref ref-type="fn" rid="fn1"&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;/xref&gt;

Production of ethylene by injured sweet potato root tissue&lt;xref ref-type="fn" rid="fn1"&gt;&lt;sup&gt;1&lt;/sup&gt;&lt;/xref&gt;

Isolation and Properties of Acid Phosphatases of Sweet Potato Roots

Acid phosphatase of sweet potato root tissue was found to consist of five components by diethylaminoethyl-cellulose column chromatography, and each component was isolated by the rechromatography. They were not separated by Sephadex G-200 gel filtration. All components hydrolyzed various phosphate compounds including phosphomonoester- and pyrophosphate-linkages. Their optimum pH values were in the range of pH 5 to 6. However, there were observed some differences in optimum pH, Michaelis constant for various substrates and relative maximum velocity among the components.

Increase of Mitochondrial Fraction in Sweet Potato Root Tissue after Wounding or Infection with Ceratocystis fimbriata

The acid-insoluble nitrogen content, lipid content, and cytochrome oxidase activity in the mitochondrial fraction are found to increase during incubation of slices of sweet potato (Ipomoea batatas) root tissue. These increases appear to be related to an increase in the number of the mitochondrial particles. The increase in the mitochondrial fraction is not accompanied by an increase in cell number. The nitrogen content in the mitochondrial fraction increases prior to the changes in the activity of cytochrome oxidase and lipid content. The increase in the numbers of the mitochondrial particles lags behind the increase in the cytochrome oxidase activity. Such findings are also found in the tissue infected by Ceratocystis fimbriata.The respiratory increase in response to wounding and infection appears to be a result of an increase in mitochondrial particles.

Biosynthesis of ipomeamarone: II. Synthetic mechanism

Radioactive ipomeamarone synthesized by black rot sweet potato root tissues incubated with acetate-2-C 14 and mevalonate-2-C 14 was oxidatively degraded by potassium permanganate, and ipomeanic acid was proved to be a major degradation product. The determination of ipomeanic acid radioactivity compared with that of ipomeamarone gave figures close to the theoretically predicted ones based on the isoprenoid rule, thus verifying this as the biosynthetic route of ipomeamarone. The enzymatic mechanism of ipomeamarone biogenesis is discussed.