Banded filaments associated with the aster yellows MLO in Vinca rosea L

The ultrastructure of an aster yellows mycoplasma-like organism was studied in the phloem of periwinkle (Vinca rosea L.) plants. Banded filaments were observed in association with mycoplasma-like organisms of characteristic morphology. The filaments were variable in length, from 50-100 nm in width, and displayed a regular periodic banding of alternating electron-dense and electron-lucent structures.     

Anti-spermatogenic effect of Vinca rosea Linn.

Regressive changes in seminiferous tubules and Leydig cells, increased cholesterol content in testis, and degeneration of all germinal elements other than spermatogonia were observed in the male Swiss albino mice, treated with aqueous extract of V. rosea leaves for 24 days. While the results reflect antiandrogenic and antispermatogenic action of V. rosea, the selective retention of the spermatogonia provides scope for the much desired revival of spermatogenesis on cessation of the treatment.     

Glucosyl Zeatin and Glucosyl Ribosylzeatin from Vinca rosea L. Crown Gall Tumor Tissue

Recently detected but unidentified cytokinin activity in crown gall tumor tissue from Vinca rosea L. grown on media containing sources of reduced nitrogen has now been attributed to two adenine-type cytokinins. These compounds are glucopyranosyl derivatives of zeatin and ribosylzeatin. The substitution in each case is on the isopentenyl chain of the parent compound. Neither of these compounds had activity in the soybean callus bioassay at concentrations lower than 1 nm whereas zeatin had activity at 0.1 nm.     

Mass spectrometric measurement of zeatin glycoside levels in Vinca rosea L. crown gall tissue

The range of zeatin glycosides found in crown gall tissue of Vinca rosea L. has been quantified using a mass spectrometric isotope dilution procedure. Problems in the quantitative analysis of cytokinins in plant extracts are discussed.Abbreviations GC/MS coupled gas chromatography-mass spectrometry - HPLC high-performance liquid chromatography - Me methyl - Z zeatin - Z9G zeatin 9-glucoside - ZOG zeatin O-glucoside - ZR zeatin 9-riboside - ZROG zeatin 9-riboside O-glucoside     

Revised Methods for Purification of Ribosyl-trans-zeatin from Vinca rosea L. Crown Gall Tumor Tissue

Ribosyl-trans-zeatin has been purified from Vinca rosea L. crown gall tumor tissue by using two new sequences of isolation procedures. Identification of the compound has been established by mass spectrometry, ultraviolet absorbancy spectra, chromatographic values, and growth activity. The isolation sequences eliminate the exposures to pH extremes and the strong cation-exchange resin used in the purification reported earlier. The initial extraction procedures have been designed so as to avoid enzymatic alteration or production of active material and to prevent the inclusion in the extracts of nucleic acids which might serve as soures of the small active compounds. The production of ribosylzeatin by the tumor tissue is confirmed and the validity of isolation steps such as the use of cation exchangers is supported.     

Zeatin-9-glucoside,a major endogenous cytokinin of Vinca rosea L. crown gall tissue

Cultured crown gall tissue of Vinca rosea L. was found to contain, in addition to the previously reported cytokinins zeatin, zeatin riboside, and the 0-glucosides of these two compounds, relatively high levels of zeatin-9-D-glucopyranoside. This is the first conclusive identification of an endogenous cytokinin 9-glucoside.Abbreviations GC gas chromatography - HPLC high-performance liquid chromatography - I.D. internal diameter - RFE rotary film evaporation - TLC thin layer chromatography - TMS trimethylsilyl - UV ultraviolet - Z zeatin - Z7G zeatin-7-glucoside - Z9G zeatin-9-glucoside - Z0G zeatin-0-glucoside - ZR zeatin riboside - ZR0G zeatin riboside-0-glucoside     

Ultrastructure of Nectaries of Vinca rosea L., Vinca major L. and Citrus sinensis Osbeck cv. Valencia and its Relation to the Mechanism of Nectar Secretion

The ultrastructural changes in nectar-secreting cells of Vincarosea, Vinca major, and Citrus sinensis during their ontogeneticdevelopment are described. The most pronounced changes occurin the amount and morphology of the endoplasmic reticulum (ER).The amount of ER elements increases gradually and reaches amaximum at the stage of secretion. At this stage the ER is thedominant element in the cytoplasm. A process of swelling ofa lamellar ER, followed by formation of vesicles, was notedin the secretory cells during the stage of secretion. Many vesicularelements appeared to be in a close association with the plasmalemma.It is suggested that sugar is secreted as a solution by meansof vesicles derived from the ER.     

The Germination of Vinca rosea L. Pollen Grains and the Growth of the Pollen Tubes in vitro

The effect of medium concentration, pollen grain concentration, pH of the media, light and temperature on the germination of Vin ca rosea pollen grains, and the growth of their pollen tubes in vitro have been studied. The pollen grains germinate best at a sucrose concentration between 14.2% and 30%; when the pollen grain concentration exceeds 800 per 0.0234 ml; at near neutral pH (6.5); in darkness and at a temperature close to 30°. Moreover buffering ions affect the growth of the pollen tubes. Pollen grains remain viable in a wide range of temperatures, and the wall of the pollen grain is capable of withstanding severe osmotic imbalance. Low temperature induces spherical swellings at the tips of the pollen tubes, followed by accumulation of a hyaline plug.     

The biosynthesis of cytokinins in crown-gall tissue of Vinca rosea

The crown-gall tissue of Vinca rosea converts labelled adenine into cytokinins. The principal initial products appear to be ribosylzeatin phosphates; zeatin and ribosylzeatin are also produced in appreciable quantities. The efficiency of conversion of adenine into cytokinins suggests a pathway of synthesis independent of turnover of tRNA. Isopentenyl adenine or its derivatives do not appear to be intermediates in the conversion of adenine to zeatin compounds. Cytokinins in V. rosea turnover rapidly and further metabolism of zeatin derivatives seems to result in their conversion into glucosides which are the main cytokinin active compounds in the tissue.Abbreviations HPLC high performance liquid chromatography - AMP adenosine monophosphate - TLC thin-layer chromatography - GLC gas-liquid chromatography     

Glucans in the Cell Walls Regenerated from Vinca rosea Protoplasts

Protoplasts prepared from suspension-cultured Vinca rosea cellswere cultured for 5 days. The cell walls regenerated from theprotoplasts were mainly composed of glucans having 1,3- and1,4-linkages. To investigate the molecular species, these glucanswere separated into four fractions: EDTA (50 mM, pH 4.5)-soluble(fraction E), KOH (24%)- soluble but not precipitatable by neutralizationwith acetic acid (fraction K-S), KOH (24%)-soluble and precipitatableby neutralization with acetic acid (fraction K-P), and KOH (24%)-insoluble(fraction C). By means of sugar composition analysis, methylationanalysis, periodate oxidation and enzymatic digestion, the molecularspecies of the glucans contained in the regenerated cell wallswere deduced to be ß-1,4-glucan (cellulose) and ß-1,3-glucan.Fraction C was mainly composed of ß-1,4-glucan; ß-1,3-glucanwas mainly recovered in fraction K-P. The ß-l,3-glucanwas soluble in dilute alkali solution, but was only slightlysoluble in water. The ß-1,3-glucan had an essentiallyunbranched structure, and its weight average molecular weightestimated by gel permeation chromatography was 4.5–5.0x 10⁴. ¹ Present address: Division of Environmental Biology, NationalInstitute for Environmental Studies, Yatabe, Tsukuba, Ibaraki305, Japan (Received May 21, 1981; Accepted October 13, 1981)     

Regulation of Aspartokinase Isoenzyme Levels in Cultured Cells of Vinca rosea

The levels of aspartokinase isoenzymes were followed as a functionof days after transfer of V. rosea cells to fresh medium. Whencells were subcultured in a 7-day cycle, both isoenzymes showedpeaks at early, but not identical, stages of cell proliferation.Levels of the intracellular amino acids lysine, threonine, isoleucineand methionine decreased as the cellular level of protein increased.As soon as the increase in protein ceased, the amino acid levelbegan to increase. The stationary cells accumulated large amountsof free amino acids. When late stationary cells were used asthe inoculum, growth was slow and, as expected, it took longerbefore the depletion of endogenous free amino acids and thedevelopment of aspartokinase isoenzymes was significantly retarded.These results are further evidence that the syntheses of aspartokinaseisoenzymes are under repression-derepression control in higherplants as they are in bacterial systems. (Received April 22, 1981; Accepted August 31, 1981)     

Effect of cycloheximide on some physiological changes associated with senescence of detached flowers of Iris germanica L.

Silverthiosulphate which is a potent inhibitor of ethylene action was found to be ineffective in delaying senescence of detached flowers of Iris germanica whereas cycloheximide, a protein synthesis inhibitor, effectively delayed the senescence of these flowers and extended the longevity to 6 days. However, this treatment resulted in suppression of bud opening. When cycloheximide treatment was given at progressive intervals it became less effective in inhibiting bud opening and delaying senescence. Cycloheximide treatment maintained a higher protein content in the perianth tissue of flowers compared to untreated flowers.     

Heterogeneity of hydroxyproline-containing glycoproteins in protoplasts from a Vinca rosea suspension culture

Protoplasts prepared from a Vinca rosea suspension culture regeneratedcell walk in culture within 24 hr. Glycoproteins containinghydroxyproline were isolated from the protoplasts prior to regenerationof the cell walls. The glycoproteins were extracted, withouta degradation procedure, with 0.05 M sodium acetate buffer,pH 5.6, containing 0.3 M NaCl. Newly synthesized hydroxyprolinein protoplasts labelled with proline appeared almost exclusivelyin the glycoproteins. In this system, the hydroxylation of prolineand the incorporation of arabinose into glycoproteins were suppressedby protein synthesis inhibitors. Inhibition of hydroxylationby the removal of Fe²⁺ also caused suppression of arabinoseincorporation into glycoproteins. These observations suggestthat glycoproteins are precursors of extensin, a hydroxyproline-richglycoprotein contained in the cell wall of plants. The precursorswere heterogeneous in size and charge as determined by gel filtrationand ion exchange chromatography. (Received February 16, 1979; )     

Cytokinins in transfer RNA of normal and crown-gall tissue of Vinca rosea

cis-Zeatin riboside was identified in transfer-RNA hydrolysates from both normal and crown-gall tissue of Vinca rosea L. The trans-isomer was associated exclusively with the crowngall transfer-RNA. The importance of these observations is discussed in relation to biosynthesis of free cytokinins.Abbreviations GC-MS gas chromatography-mass spectrometry - HPLC high-performance liquid chromatography - TLC thin-layer chromatography - TMSi trimethylsilyl - tRNA transfer RNA - ZR zeatin riboside     

In vitro synthesis of spermidine in the higher plant, Vinca rosea

Cell-free extracts of $\text{Vinca rosea}$ seedlings exhibited enzyme activities for the following reactions: S-adenosyl-L-methionine (SAM) decarboxylation, spermidine synthesis from decarboxylated SAM and putrescine, and 5′-methylthioadenosine hydrolysis to 5-S-methyl-5-thio-D-ribose and adenine. SAM decarboxylation was stimulated by putrescine and inhibited by semicarbazide. The 15-fold purified ribohydrolase possessed a K_m of 1. 03 × 10^?5 M and a high specificity for 5′-methylthioadenosine.