Vegetable Marrow Research Articles

Resistance in vegetable marrow and other Cucurbita spp. to two British strains of cucumber mosaic virus

SummaryMost commercial cultivars of Cucurbita pepo L. reacted by producing severe leaf symptoms when infected with either of two British strains of cucumber mosaic virus. Resistance was identified in some pumpkin-types of C. pepo, with the highest level in cv. Cinderella. Studies with selfed populations produced from selected resistant plants demonstrated that resistance in cv. Cinderella is heritable.

Septoria cucurbitacearum . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Septoria cucurbitacearum . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Cucumis melo, C. sativus, Cucurbita ficifolia (= C. melanosperma ), C. maxima, C. moschata, C. pepo and Bryonia dioica (= B. cretica ). DISEASE: Leaf spot of cantaloupe, cucumber, melon, pumpkin, squash and vegetable marrow. The visible symptoms are circular, olive brown lesions, prominent on the upper surface of the leaves. With the progress of the disease the spots enlarge, usually reaching 3-5 mm diam., occasionally 8 mm wide and soon dry up. Older lesions tend to turn white revealing several pycnidia embedded within the tissue. GEOGRAPHICAL DISTRIBUTION: Africa (Ethiopia, Kenya, Zambia); Australasia & Oceania (Australia); Europe (Bulgaria, Denmark, France, Germany, Hungary, Italy, Portugal, Rumania, USSR); North America (USA, Delaware, Massachusetts, New Hampshire, New York, Pennsylvania, Wisconsin). TRANSMISSION: Presumably by conidia disseminated by water splash in wet weather or heavy dews.

Kinetics of leaf nitrite reductase with Methyl Viologen and ferredoxin under controlled redox conditions

Some factors that influence the activity of nitrite reductase (EC 1.7.7.1) were investigated, the enzyme from Curcurbita pepo (vegetable marrow) being used. The activity with ferredoxin or Methyl Viologen as electron donor was inhibited by certain salts, including NaCl. The steady-state kinetic parameters measured in a commonly used open-tube (aerobic) system were compared with a closed-cell (anaerobic) system in which the redox potential, and thus the concentrations of oxidized and reduced donor, could be controlled. This showed that in the open-tube system the apparent Km values determined were overestimated (by a factor of 10 for reduced Methyl Viologen), owing to incomplete mediator reduction and competitive inhibition by the oxidized form of the mediator.

Third-harmonic detection of electron-paramagnetic-resonance spectra: resolution of the hyperfine splitting in nitrosylated nitrite reductase from vegetable marrow (Cucurbita pepo).

Derivative spectroscopy has often been used in n.m.r. and optical-absorption spectroscopy as a means of resolving narrow features obscured by broad lineshapes. E.p.r. spectra are normally presented as the first-harmonic (first derivative) form, but higher harmonics can readily be generated by modulating the magnetic field at a subharmonic frequency and operating the phase-sensitive detector at a multiple of that frequency (Chevion et al. 1977). As a result, the features are sharpened at the expense of a more complex lineshape. The nitrite reductase of higher plants yields a complex with an e.p.r. spectrum at g = 2.060, 2.007 (Aparicio et al., 1975) that appears to be an intermediate in the enzyme reaction (Cammack

A lectin from the exudate of the fruit of the vegetable marrow (Cucurbita pepo) that has a specificity for beta-1,4-linked N-acetylglucosamine oligosaccharides.

Lectins are present in the exudate (presumably from the phloem) of the fruits of three species of the Cucurbitaceae, namely vegetable marrow (Cucurbita pepo), melon (Cucumis melo) and cucumber (Cucumis sativus). They are all strongly inhibited in their activities by chitin oligosaccharides, but only weakly by N-acetylglucosamine. Glycopeptides from soya-bean agglutinin and fetuin are also strong inhibitors of Cucurbita pepo lectin, indicating that it interacts with internal N-acetylglucosamine residues. The lectin from Cucurbita pepo fruit was purified by affinity chromatography by using chitin oligosaccharides covalently attached to Sepharose. The lectin is not a glycoprotein, and it consists of a single polypeptide chain of about 20,000 mol.wt. It is a major protein (18% of the total) of the phloem exudate and it is postulated that it may have an anti-parasitic function.

Electron-paramagnetic-resonance studies of the mechanism of leaf nitrite reductase. Signals from the iron–sulphur centre and haem under turnover conditions

Low-temperature e.p.r. spectra are presented of nitrite reductase purified from leaves of vegetable marrow (Cucurbita pepo). The oxidized enzyme showed a spectrum at g=6.86, 4.98 and 1.95 corresponding to high-spin Fe(3+) in sirohaem, which disappeared slowly on treatment with nitrite. The midpoint potential of the sirohaem was estimated to be -120mV. On reduction with Na(2)S(2)O(4) or Na(2)S(2)O(4)+Methyl Viologen a spectrum at g=2.038, 1.944 and 1.922 was observed, due to a reduced iron-sulphur centre. The midpoint potential of this centre was very low, about -570mV at pH8.1, decreasing with increasing pH. On addition of cyanide, which binds to haem, and Na(2)S(2)O(4), the iron-sulphur centre became further reduced. We think that this is due to an increased midpoint potential of the iron-sulphur centre. Other ligands to haem, such as CO and the reaction product NH(3), had similar but less pronounced effects, and also changed the lineshape of the iron-sulphur signal. Samples were prepared of the enzyme frozen during the reaction with nitrite, Methyl Viologen and Na(2)S(2)O(4) in various proportions. Signals were interpreted as due to the reduced iron-sulphur centre (with slightly different g values), a haem-NO complex and reduced Methyl Viologen. In the presence of an excess of nitrite, the haem-NO spectrum was more intense, whereas in the presence of an excess of Na(2)S(2)O(4) it was weaker, and disappeared at the end of the reaction. A reaction sequence is proposed for the enzyme, in which the haem-NO complex is an intermediate, followed by other e.p.r.-silent states, leading to the production of NH(4) (+).

Damping‐off of Cucurbitaceous Plants in Egypt V. Reaction of vegetable Marrow, watermelon and cucumber to certain isolates of Rhizoctonia solani

Damping‐off of Cucurbitaceous Plants in Egypt V. Reaction of vegetable Marrow, watermelon and cucumber to certain isolates of <i>Rhizoctonia solani</i>

Properties of nitrite reductase from Cucurbita pepo

Nitrite reductase purified to homogeneity from vegetable marrow contains 2 atoms Fe/mol. Enzyme-bound iron exchanged extremely slowly with 59-Fe in solution. Acid-acetone extracts of the enzyme have a spectrum which is consistent with the presence of a sirohaem prosthetic group. Inhibition by mersalyl, which partially bleaches the enzyme, is reversible by glutathione only if this is added within a few min of mersalyl. The absorption spectra of the reduced and autoxidised enzyme and of the nitrite, cyanide and CO complexes are described. Amino acid composition data are given. The hydroxylamine reductase activity of the purified enzyme was 0.2% of nitrite reductase activity.

Effect of Cucumber Mosaic Virus Infection on the Amino Acids and Amides in Vegetable Marrow Leaves

Effect of Cucumber Mosaic Virus Infection on the Amino Acids and Amides in Vegetable Marrow Leaves

The amino acid sequence of plastocyanin from Cucurbita pepo L. (vegetable marrow).

The amino acid sequence of plastocyanin from marrow was determined. It consists of a single polypeptide chain of mol.wt. 10284 containing 99 amino acid residues. The sequence was determined by using a Beckman 890C automatic sequencer and by dansyl-phenyl isothiocyanate analysis of peptides obtained by the enzymic digestion of purified CNBr fragments. The sequence is in good agreement with the amino acid composition, except that fewer residues of glutamic acid were found in the sequence than were suggested by the composition. Evidence for histidine-37 was weaker than for the rest of the sequence. A ;tree' of phylogenetic affinities was constructed by using several higher-plant plastocyanin sequences.

Fusarium javanicum Koorders in Israel.

Fusarium javanicum Kds. has been isolated from wilted vegetable marrows and melons and from the soil of a citrus grove in Israel. The morphology of the species is described, and measurements and drawings of macroconidia are presented.In vitro tests showed thatF. javanicum failed to develop at either 12 or 40° C, and developed better at 24° C than 18 or 30° C. Mycelial growth on potato dextrose agar was always better at pH 7 than at pH 4.2. Darkness favored such growth to a marked extent only at 18° C and pH 4.2. In glasshouse inoculation tests one isolate ofF. javanicum from vegetable marrow proved clearly pathogenic to cucumber, melon, watermelon and marrow. Measurements of macroconidia have been made, for comparative purposes, on isolates ofF. javanicum var.ensiforme and ofF. solani f.cucurbitae furnished from abroad, and on isolates ofF. solani from cucurbits in Israel. Comparing the data for 3-septate macroconidia with those given in literature forF. solani and forF. javanicum and its var.radicicola and var.ensiforme, it is concluded that two groups can be distinguished: One group comprises, with one exception, all isolates ofF. javanicum and its varieties as well asF. solani f.cucurbitae, and is characterized by slender macroconidia. The other group is represented byF. solani with its typically sausage shaped conidia. It is concluded thatF. javanicum should be maintained as a species distinct fromF. solani. It is further suggested that what has been calledF. solani f.cucurbitae may have closer affinity toF. javanicum than toF. solani.

Nitrite and hydroxylamine reduction in higher plants. Fractionation, electron donor and substrate specificity of leaf enzymes, principally from vegetable marrow (Cucurbita pepo L.).

Nitrite reductase was purified between 760- and 1300-fold from vegetable marrow (Cucurbita pepo L.) and residual hydroxylamine reductase activity was low or negligible by comparison. With ferredoxin as electron donor, nitrite loss and ammonia formation at pH7.5 were stoicheiometrically equivalent. Crude nitrite reductase preparations showed negligible activity with NADPH as electron donor maintained in the reduced state by glucose 6-phosphate, whereas by comparison, activity was high when either ferredoxin or benzyl viologen were also present and reduced by the NADPH-glucose 6-phosphate system, whereas FMNH(2) produced variable and relatively low activity under the same conditions. At pH values below 7, non-enzymic reactions occurred between reduced benzyl viologen and nitrite, and intermediate reduction products were inferred to be produced instead of ammonia. Activity with ferredoxin (0.1mm), reduced by chloroplast grana in the light, was 25 times that produced with ferredoxin (40mum) reduced with NADPH and glucose 6-phosphate. For an approximate molecular weight 61000-63000 derived by chromatography on Sephadex G-100 and G-200, and a specific activity of 46mumol of nitrite reduced/min per mg of protein with light and chloroplast grana, a minimum turnover number of 3x10(3)mol of nitrite reduced/min per mol of enzyme was found. Two hydroxylamine reductases were separated on Sephadex gels. One (HR1) was initially associated with nitrite reductase during gel filtration but disappeared during later fractionation. This HR1 fraction showed nearly comparable activity with reduced benzyl viologen, ferredoxin or FMNH(2). The other (HR2), of molecular weight approx. 35000, reacted with reduced benzyl viologen but showed negligible activity with ferredoxin or NADPH. Activity with FMNH(2) was associated with an irregular trailing boundary during gel filtration, with much diminished activity in the HR2 region. Activity with NADPH was about 30% of that with FMNH(2), reduced benzyl viologen or ferredoxin and was considered to reside in fraction HR1. Hydroxylamine yielded ammonia under all assay conditions. No activity with hyponitrite or sulphite was observed with reduced benzyl viologen as electron donor in either the nitrite reductase or the hydroxylamine reductase systems, but pyruvic oxime produced about 4% of the activity of hydroxylamine.

Possible sites in nitrite reductase and hydroxylamine reductases from vegetable marrow (Cucurbita pepo L).

Research Article| April 01 1970 Possible active sites in nitrite reductase and hydroxylamine reductases from vegetable marrow (Cucurbita pepo L.) D P Hucklesby; D P Hucklesby Search for other works by this author on: This Site PubMed Google Scholar E J Hewitt; E J Hewitt Search for other works by this author on: This Site PubMed Google Scholar D M James D M James Search for other works by this author on: This Site PubMed Google Scholar Biochem J (1970) 117 (2): 30P. https://doi.org/10.1042/bj1170030Pa Views Icon Views Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Icon Share Twitter LinkedIn Cite Icon Cite Get Permissions Citation D P Hucklesby, E J Hewitt, D M James; Possible active sites in nitrite reductase and hydroxylamine reductases from vegetable marrow (Cucurbita pepo L.). Biochem J 1 April 1970; 117 (2): 30P. doi: https://doi.org/10.1042/bj1170030Pa Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentAll JournalsBiochemical Journal Search Advanced Search This content is only available as a PDF. © 1970 The Biochemical Society1970 Article PDF first page preview Close Modal You do not currently have access to this content.

The Feasibility of Introducing Squash Bees (Peponapis and Xenoglossa) Into the Old World

The introduction of honeybees from the Old World to the New has been of the utmost significance, for the pollination of agricultural crops as well as for honey and wax production. And in New Zealand, red clover seed crops failed until bumble bees were introduced from England. The New World, as well as the Old, is rich in native wild bees, and the present article discusses the question of introducing to the Old World from the New certain species of “squash bees”, so called because they are especially adapted for pollinating squashes and other species of Cucurbita (gourds, pumpkins and vegetable marrows).

The Tale of the Ungrateful Grandfather

Once there was a man who went to Itumba, Ukaguru, in the east, to get some vegetable marrow seeds. On his return with a special type of marrow, he said to his wife, 'I brought this marrow from the east, a type of marrow the foreigners have. Oh it'll be wonderful, very tasty!' When the rains came they sowed the seeds in their field. As they put the seeds in, they turned the soil properly and they also planted something to indicate which the special marrow was. The husband said in satisfaction, 'This seed which I have sowed is of the marrow I brought from Itumba'. They tended the plot very carefully, weeding it several times. One day when he went there, the husband saw that all the marrow plants which had sprouted had not flowered, but that one had. 'Ah, this marrow plant I brought from Itumba has begun to bear'. And when he came on the following morning he found the plant had borne a large fruit, just overnight. Yesterday it had merely a flower, now a huge marrow!

Preparation of dried vegetable marrows for winter use in north manchuria

It is well known that the diet of the Chinese consists in great part of vegetable products. This people cultivate many kinds of vegetables which are consumed usually when they are fresh. In the northern provinces of China, however, some kinds of fresh vegetables are not available during the cold period of the year. They, therefore, are preserved for winter use in a variety of ways. One of these ways, for instance, is the preparation of dried strings cut from vegetable marrow (Cucurbita pepo L.), which I have seen widely practiced in the North Manchurian countryside. This product is usually prepared in the late summer and beginning of autumn, when it is the end of the season of vegetable marrows. The fruit of the marrow is placed vertically on a pointed rod mounted on a bench and cut spirally in long and narrow strings

CELLULASE IN TOMATO FRUITS.

THERE are only a few reports of enzymes from higher plants which can hydrolyse cellulose or water-soluble cellulose derivatives. Several reports show that malt extracts are capable of hydrolysing water-soluble cellulose derivatives1,3,11 and dispersed cellulose fibres1,7. A malt extract was found to hydrolyse reprecipitated cellulose more rapidly than a similar extract from barley seeds1. There is a single report that potato sprouts hydrolysed the cellulose in cardboard8. Another report10 showed that sap from tobacco leaves and roots hydrolysed carbpxy-methylcellulose and reprecipitated cellulose. In addition to tobacco, cellulase was found on single occasions in bean leaves, roots of beet and woody nightshade, asparagus stems, and the flesh of vegetable marrow fruit. The enzyme was not detected in tomato fruits or rhubarb petioles which had pH. values of 4.3 and 3.4 respectively. The author mentioned that the pH. was greater than 5 in all the saps in which activity was found.

Ascorbic acid in chloroplasts.

ASCORBIC acid is found in all green plants, although its concentration may vary greatly. Probably the largest concentration recorded is in the endocarp of the walnut, Juglans regia, which contains between 2 and 3 per cent of the fresh weight. The smallest concentration recorded is possibly that in the vegetable marrow, Cucurbita ovifera, 0.002 per cent of fresh weight. The ascorbic acid in green leaves is generally between 0.05 and 0.5 per cent of the fresh weight, and is usually in higher concentration there than in the remainder of the plant.

The life-history of the melon weevil, Baris granulipennis (Tourn.), in Israel

Baris granulipennis (Tourn.), originally described from Egypt, has become a serious pest of water-melons (Colocynthis citrullus) in Israel, where hitherto its presence has not been recorded, and has been found on melons and cucumbers, but not on vegetable marrow or squash. Economically serious damage results from girdling of the stem end of the fruit by the female, prior to oviposition.The incubation period of the egg, on average, is 3·7 days at 30° and 6 days at 22°C. The larvae feed on developing seeds inside the fruit and pupate there. The total development period occupied from 25 to 42 days in the summer, when the temperature fluctuated between 24 and 29°C. The cocoon is made by glueing minute pellets together. These consist of dried pulp from the fruit mixed with a secretion which is ‘milked’ from the anus, and is believed to be produced in the Malpighian tubules. The preoviposition period is about four days, and the length of adult life is several weeks. There are three generations a year, and four if weather permits. Adults overwinter in hibernation. It is suggested that the increase of cucurbit cultivation, and the lengthening, by irrigation, of the cropping period, may have permitted an increase in the weevil population to pest proportions.

EXPERIMENTS AND OBSERVATIONS ON A VIRUS DISEASE OF WINTER SPINACH (SPIN ACIA OLERACEA)

SummaryA disease of winter spinach common in the Thames Valley has been shown to be of a virus nature. It is characterized by a mottling and malformation of the leaves, stunting of growth and death of the plants. The causal agent has been shown to be identical with cucumber mosaic I of Ainsworth.The disease is most prevalent in the earlier sown crops, and this appears to be correlated with their liability to be infested with aphides. Field observations on a number of farms indicated a correlation between intensity of aphis infestation and intensity of disease.Seed‐borne infection, though possible, has not been proved.Under field conditions in the Thames Valley it is suggested that a main source of contamination of winter spinach is the outdoor vegetable marrow crop.Postponement of date of sowing until the latter half of September is suggested as a method of reducing the amount of disease.