Biosynthesis of C20-carotenoids in Crocus sativus

Phytoene, phytofluene, tetrahydrolycopene, β-carotene, zeaxanthin and crocetin were isolated from Crocus sativus. The absence of C₂₀-hydrocarbon precursors of crocetin supports a degradation pathway for the biosynthesis of crocetin.     

Biosynthesis and metabolism of steryl glycosides in Sinapis alba seedlings

With ¹⁴CO₂, d-glucose-[U-¹⁴C] and dl-mevalonate-[4R-4-³H₁] used as precursors, a study was made of the labelling dynamics of the steryl glucosides (SG) and steryl acylglucosides (ASG) in Sinapis alba seedlings. The radioactivity of the sterol and sugar moieties, as well as of the fatty acid moieties in the case of ASG, was analysed separately. The course of incorporation of ¹⁴C from ¹⁴ CO₂ and glucose-[U-¹⁴C] into the sugar part of SG and ASG indicated that about $\text{2}\text{3}$ of the whole pool of the newly synthesized sterol glycosides of both types underwent rapid deglucosylation. Likewise, fatty acids in the ASG pool were rapidly exchanged. The present results point to a high metabolic activity of the sterol glycoside derivatives in plant cells.     

12-disinapolylglucose accumulated in cotyledons of dark-grown raphanus sativus seedlings

A new sinapic acid ester has been isolated and characterized as 1(E),2(E)-di-O-sinapoyl-β-d-glucopyranoside from cotyledons of dark-grown red radish (Raphanus sativus) seedlings. Its structure was elucidated by negative ion fast atom bombardment mass spectrometry, ¹H and ¹³C NMR spectra and enzymatic determination of the glucose moiety. A possible biosynthetic mechanism for the formation of this new ester is discussed in which the energy-rich acyl glucoside 1-O-sinapoyl-β-d-glucose acts as the acyl donor in a sinapoyl transfer to the hydroxyl group at C-2 of the glucose moiety of another molecule of 1-O-sinapoyl-β-d-glucose (‘disproportionation’).     

De novo assembly and characterization of the complete chloroplast genome of radish (Raphanus sativus L.)

Radish (Raphanus sativus L.) is an edible root vegetable crop that is cultivated worldwide and whose genome has been sequenced. Here we report the complete nucleotide sequence of the radish cultivar WK10039 chloroplast (cp) genome, along with a de novo assembly strategy using whole genome shotgun sequence reads obtained by next generation sequencing. The radish cp genome is 153,368 bp in length and has a typical quadripartite structure, composed of a pair of inverted repeat regions (26,217 bp each), a large single copy region (83,170 bp), and a small single copy region (17,764 bp). The radish cp genome contains 87 predicted protein-coding genes, 37 tRNA genes, and 8 rRNA genes. Sequence analysis revealed the presence of 91 simple sequence repeats (SSRs) in the radish cp genome.     

Herbicides which inhibit photosystem II or produce chlorosis and their effect on production and transformation of pigments in etiolated radish seedlings (Raphanus sativus)

Abstract The herbicides DCMU, bentazon, amitrole, and SAN 6706 were tested for their ability to influence the carotenoid and pro-tochlorophyll(ide) composition as well as the protochloro-phyll(ide) phototransformation and the Shibata shift in dark-grown radish seedlings (Raphanus sativus L. cv. Saxa Treib). Bentazon enhanced the formation of lutein and carotenes, while SAN 6706 suppressed the biosynthesis of carotenoids. Amitrole led to a reduced accumulation of phototransformable pro-tochlorophyll(ide). The phototransformation of pro-tochlorophyll(ide) and the Shibata shift were not affected by any of the tested herbicides, irrespective of the presence or absence of activated phytochrome. From this we conclude that herbicides inhibiting photosystem II or producing chlorosis partly affect, but do not block, carotenoid and chlorophyll biosynthesis in dark-grown plants. The main herbicide effect becomes visible only after prolonged illumination.     

2-O-(p-Coumaroyl)-l-Malate, 2-O-Caffeoyl-l-Malate and 2-O-Feruloyl-l-Malate in Raphanus sativus

The cotyledons, leaves and inflorescences of the radish, Raphanus sativus, have been examined for their content of hydroxylated cinnamic acid malate esters. 2-O-(p-coumaroyl)-l-malate, 2-O-caffeoyl-l-malate and 2-O-feruloyl-l-malate were found to be quantitatively predominating compounds in the fraction of carboxylic acids isolated from radish leaves and inflorescences. Identifications were based on PC, TLC, HVE, GC, HPLC, UV and NMR spectroscopy. The l- or (2S)-configuration of malic acid released by hydrolysis from the esters was determined by using l-malate dehydrogenase. A combined column chromatography technique applied prior to HVE, HPLC and GC was useful for separating the malate esters from most other low MW plant constituents. The significance of the present investigation is briefly discussed in relation to the metabolism of phenolic constituents of glucosinolate-containing plants, and the effects of these compounds in relation to insect feeding behaviour.     

Amo 1618 and sterol biosynthesis in tissues and sub-cellular fractions of tobacco seedlings

Amo 1618 inhibited the incorporation of MVA-[2-¹⁴C] into sterols (in particular the 4-desmethylsterols) and promoted its accumulation in squalene-2,-3epoxide in intact seedlings, tissues from treated seedlings, and sub-cellular, membraneous fractions of treated 21-day-old tobacco seedlings. The stem tissues appeared to have a greater sterol requirement (on a per gram fresh weight basis) than leaf tissues and incorporation of radioactivity into stem sterols was more susceptible to inhibition by Amo 1618 than incorporation into leaf tissue.     

The carotenoids of Rhodomicrobium vannielii (rhodospirillaceae) and the effect of diphenylamine on the carotenoid composition

The presence of β-carotene, lycopene, rhodopin, rhodovibrin, anhydrorhodovibrin, spirillox-anthin, ‘monodemethylated spirilloxanthin’ and ‘dihy     

Chlorophylls and carotenoids of the marine alga Eutreptiella gymnastica

Monoalgal cultured Eutreptielia gymnastica contained chlorophyll a and b. The acetylenic carotenoids diatoxanthin and diadinoxanthin were among the main xanthophylls while their non-acetylenic analogues zeaxanthin and antheraxanthin were absent. The structurally most complex carotenoid was identical with neoxanthin. Three of the xanthophylls isolated could not be positively correlated with carotenoids previously reported from the Euglenophyceae. The ketocarotenoids astaxanthin, canthaxanthin and echinenone were absent.     

Seed coat carotenoids of the cycad genera Dioon,Encephelartos, Macrozamia and Zamia: Evolutionary significance

Seed coat carotenoids of Dioon, Encephelartos, Macrozamia and Zamia with ranges in Africa, the West Indies, Australia and Mexico are simple mixtures which conform to the theoretical primitive angiosperm “magnolian pattern”. Lycopene is the principal pigment of Zamia while Encephelartos, Dioon and Macrozamia coats contain a mixture of the unsubstituted, mono-and di-hydroxy-β-carotenes. The evolutionary significance of these results is discussed.     

Free and bound sterols in seedlings of Cucumis sativus

Free sterols, sterol esters, sterol monoglucosides and sterol acylmonoglucosides have been obtained from 10 days old seedlings of Cucumis sativus. Free sterols and sterol esters consist mainly of Δ⁷ di- and triunsaturated sterols, whereas Δ⁷ mono-unsaturated and Δ⁵ mono- and diunsaturated sterols predominate in the glucosides and acylglucosides. Both acetates and derivatives of higher fatty acids, mainly linoleic and linolenic acids, have been found in the sterol esters. Sterol acylglucosides contain mostly saturated fatty acids, palmitic and stearic acids being the main components.     

3-Methylthiopropylamine and (R)-3-methylsulphinylpropylamine in Iberis amara

3-Methylthiopropylamine and (R)-3-methylsulphinylpropylamine have been isolated from Iberis amara and identified by PC, high voltage electropho     

Changes in the chlorophylls and carotenoids of leaves of Nicotiana tabacum during senescence

In addition to chlorophylls a and b, β-carotene, lutein, violaxanthin and neoxanthin, leaves of tobacco (Nicotiana tabacum L. cv. Virginia Gold) contain antheraxanthin in some harvests. In lower leaves, chlorophylls decreased more rapidly than carotenoids during senescence, but both types of pigment decreased at equal rates in upper leaves. The chlorophyll a:b ratio decreased only in post-mature leaves. Total carotenoid decreased with age, with the relative proportion of β-carotene increasing in lower leaves. Seasonal influences rather than age of leaf determines whether antheraxanthin is present. No esterified xanthophylls were found in senescent leaves.     

Investigation of Brassica oleracea and Nasturtium officinale seeds for the presence of epithiospecifier protein

Cabbage seeds contain 5 glucosinolates and on autolysis produce, in particular, 1-cyano-2-3-epithiopropane. Watercress seeds contain 4 glucosinolates, but none capable of forming a cyanoepithioalkane. Cabbage exhibited behaviour commensurate with possession of an epithiospecifier protein (ESP) whilst watercress did not show any such activity.     

1,3-Diaminopropane and spermidine in cucumis sativus (cucumber)

1,3-Diaminopropane has been detected, together with spermidine, in cucumber seeds. Quantitative estimation of the two metabolites in cucumber seeds and germinating seedlings (up to 21 days old) showed that the concentrations of both metabolites increased, then decreased with age. A metabolic sequence linking spermidine, 1,3-diaminopropane and the non-protein amino acid β-pyrazol-1-yl alanine was suggested.     

GH3 expression and IAA-amide synthetase activity in pea (Pisum sativum L.) seedlings are regulated by light,plant hormones and auxinic herbicides

The formation of auxin conjugates is one of the important regulatory mechanisms for modulating IAA action. Several auxin-responsive GH3 genes encode IAA-amide synthetases that are involved in the maintenance of hormonal homeostasis by conjugating excess IAA to amino acids. Recently, the data have revealed novel regulatory functions of several GH3 proteins in plant growth, organ development, fruit ripening, light signaling, abiotic stress tolerance and plant defense responses. Indole-3-acetyl-aspartate (IAA-Asp) synthetase catalyzing IAA conjugation to aspartic acid in immature seeds of pea (Pisum sativum L.) was purified and characterized during our previous investigations. In this study, we examined the effect of auxin and other plant hormones (ABA, GA, kinetin, JA, MeJA, SA), different light conditions (red, far-red, blue, white light), and auxinic herbicides (2,4-D, Dicamba, Picloram) on the expression of a putative GH3 gene and IAA-amide synthesizing activity in 10-d-old pea seedlings. Quantitative RT-PCR analysis indicated that the PsGH3-5 gene, weakly expressed in control sample, was visibly induced in response to all plant hormones, different light wavelengths and the auxinic herbicides tested. Protein A immunoprecipitation/gel blot analysis using anti-AtGH3.5 antibodies revealed a similar pattern of changes on the protein levels in response to all treatments. IAA-amide synthetase activity determined with aspartate as a substrate, not detectable in control seedlings, was positively affected by a majority of treatments. Based on these results, we suggest that PsGH3-5 may control the growth and development of pea plants in a way similar to the known GH3 genes from other plant species.     

The stereochemistry of hydroxylation of the carotenoid lutein in Calendula officinalis

Excised, opening inflorescences of Calendula officinalis incorporated (3RS, 5R)- and (3RS, 5S)-[2-¹⁴C,5-³H₁]mevalonates into the carotenoid fraction. The ¹⁴C:³H ratios of lutein isolated from these tissues showed the hydrogen atom at C-3 of the β-ring is derived from the 5-pro-S position of mevalonate, while that at C-3 of the ε-ring is derived from the 5-pro-R position of mevalonate. Oxidation of lutein to monoketolutein showed that both hydrogen atoms at the C-15,15′ central double bond are derived from the 5-pro-R position of mevalonate.     

Volatiles from the epicuticular wax of watercress (Rorippa nasturtium-aquaticum)

Volatiles from the epicuticular wax of watercress were collected by ether washing and examined using gas chromatographic and mass spectrometric analysi     

Activities of enzymes of amino-acid metabolism in Pennisetum seedlings grown in the presence of 2-chloroethylphosphonic acid

The plant growth regulator 2-chloroethylphosphonic acid (CEPA) slightly inhibited the elongation of growth in Pennisetum typhoides seedlings, but greatly stimulated the activity of alanine aminotransferase (GPT), asparate aminotransferase (GOT), as well as glutamate dehydrogenase (GLDH).     

The carotenoid pigments in the juice and flavedo of a mandarin hybrid (Citrus reticulata) cv michal during ripening

The carotenoid pigments ofthe mandarin hybrid (Citrus reticulata) cv Michal, in the juice and flavedo were characterized at three ripening stages, before, during and after colour break. During ripening the characteristic mandarin pattern was formed in the juice, which contained cryptoxanthin as the principal pigment. In the flavedo the chloroplast carotenoid pattern of the green fruit changed into the characteristic pattern of C. reticulata with a high level of citraurin which, together with cryptoxanthin, imparts an intensive reddish tint to the hybrid. The flavedo contained an unusual C₃₀ apocarotenoid, β-citraurinene (8′-apo-β-caroten-3-ol). The flavedo carotenoids of this accidental hybrid were compared with the carotenoids of the presumed parents Dancy tangerine and Clementine. The hybrid resembles more the second parent, from which it inherited the ability to biosynthesize a higher amount of citraurin as well as citraurinene. Citraurinene, considered a Citrus hybrid-specific pigment, was found for the first time in a Citrus variety. A possible biosynthetic pathway of the Citrus C₃₀ -apocarotenoids is proposed.