Iridoids from Galium mollugo

From Galium mollugo, two new iridoids, gardenosidic acid and 10-hydroxymorroniside as well as 10-hydroxyloganin have been isolated, along with seven known iridoids, secogalioside, asperuloside, asperulosidic acid, daphylloside, monotropein, scandoside and scandoside methyl ester. 10-Hydroxyloganin, a compound which was previously considered to be the key biosynthetic intermediate of secoiridoids, was obtained for the first time from a natural source.     

Biosynthesis of anthraquinones and related compounds in Galium mollugo cell suspension cultures

From Galium mollugo cell suspension cultures, 1,4-dihydroxy-3-prenyl-2-naphtholic acid methyl ester diglucoside was isolated along with anthraquinones and mollugin. Production of the diglucoside was much increased by administering 2-succinylbenzoate to the cultures. The incorporation of 2-succinylbenzoate into lucidin-3-primeveroside, mollugin and the diglucoside in the mode so far proposed for rubiaceous anthraquinones was verified by administration of ¹³C-labelled 2-succinylbenzoate to the cell cultures.     

The role of nodal and internodal responses in gravitropism and autotropism in Galium aparine L

Abstract This time course and location of gravitropically induced curvatures in stems of goosegrass (Galium aparine L.), a member of the Rubiaceae, have been investigated. In the early stages of the response (0–5 h), curvature develops throughout the growing region, and is followed by an autotropic straightening which affects the internodes only, leading to the production of essentially straight internodes some 15 h after the onset of gravistimulation. Curvatures developing in the nodal regions, however, continue to increase over this period, and are not subject to reversal by autotropism. The nodal curvatures are not entirely dependent on the presence of any other part of the plant, since marked curvatures can be induced in isolated nodal segments. This pattern of response leads ultimately to correction of the growth direction of the plant by means of curvature responses confined exclusively to the nodes, despite the initial participation of both nodes and internodes in the gravitropic reaction.     

Materials for Chinese Galium L. (Rubiaceae)

This paper presents an introduction to the materials for Chinese Galium Linn. (Rubiaceae). Thirteen species and eight varieties are recorded in the paper. Among these, two species and two varieties are new, eleven species and five varietiesare new to China, and one variety is a new grade.     

Growth Regulation of Galium mollugo L. Cell Suspensions by a-Naphthalene Acetic Acid

Fidgeon, C. and Wilson, G. 1987. Growth regulation of Galiummollugo L. cell suspensions by -naphthalene acetic acid.—J.exp. Bot. 38: 1491–1500. Galium mollugo cell suspension cultures were found to requirethe plant growth regulator -naphthalene acetic acid (-NAA) forcontinued growth and cell division. This requirement could notbe substituted in either batch or semi-continuous culture byindole-3-acetic acid (IAA) or 2,4-dichlorophenoxy acetic acid(2,4-D) at any concentration tested. However, ß-naphthaleneacetic acid (ß-NAA) and indole-3-butyric acid (IBA)were found to support growth when supplied at a concentrationtwo orders of magnitude greater than the normal media level(0–5 mg dm³). The growth of Galium cells was found to be influenced not onlyby the -NAA initially supplied in the medium but also by theexposure to -NAA in previous growth cycles. Preculture of cellsfor 3 d in an -NAA containing medium, followed by cell washingand re-inoculation into -NAA free medium, supported a quantitativegrowth response similar to that obtained after 14 d in the control-NAA containing medium. Even short-term exposures between 0·5and 6·0 h stimulated a detectable growth response 14d later. These observations raise questions relating to theuptake and perception of exogenously supplied growth regulatorsby cultured cells. The delayed kinetics of this form of response is of significancein culture regimes in which cells are transferred from one mediumto another, differing in their growth regulator composition,in order to induce morphogenesis     

Biosynthesis of Anthraquinone by Cells of Galium mollugo L. Grown in a Chemostat with Limiting Sucrose or Phosphate

Growth and anthraquinone biosynthesis by Galium cells were examinedin steady-state substrate-limited conditions using a chemostatcontinuous culture technique. Steady-state growth was obtainedin both sucrose- and phosphate-limiting conditions for periodsup to 60 d. In sucrose-limiting conditions three growth rateswere investigated with doubling times (t_d) of 25 h, 35 h and40 h, and phosphate-limited growth was obtained at t_d= 35 h.The kinetics of the growth response to a change in limitingsubstrate concentration in sucrose-limiting conditions was examinedand found to follow closely that predicted by the applicationof Monod's (1950) model obtained for micro-organisms. The anthraquinone content of cells grown in phosphate and sucroselimitation was uniformly similar and at a relatively low level(0.68 mg g^–1 dry wt.). When the substrate limitation wasrelieved by the addition of the limiting substrate, either phosphate,or sucrose, anthraquinone synthesis was markedly stimulated.The addition of the anthraquinone precursor, orthosuccinyl benzoicacid (OSB) greatly enhanced anthraquinone synthesis in phosphate-limitingconditions but not in sucrose-limited cells. The results show that growth limitation by phosphate and bysucrose causes a suppression of the rate of synthesis of thesecondary metabolite anthraquinone in Galium cells and suggeststhat the metabolic point of suppression is different in eachcase. Key words: Anthraquinone biosynthesis, Galium, Continuous culture, recursor feeding     

Antifeedant activity of an anthraquinone aldehyde in Galium aparine L. against Spodoptera litura F

The insect antifeedant anthraquinone aldehyde nordamnacanthal (1,3-dihydroxy-anthraquinone-2-al) was identified in Galium aparine L., and isolated from the root powder of akane (Rubia akane), a member of the Rubiaceae. Structure-activity relationship (SAR) studies using a series of anthraquinone analogues suggested that the aldehyde group on the anthraquinone was more important than the quinone moiety for antifeedant activity against the common cutworm (Spodoptera litura). High levels of nordamnacanthal were found in the seed leaf stage and in callus tissue induced from seedlings of G. aparine, but its concentration decreased with plant development. Since these compounds are natural pigments for dying textiles, we also evaluated the antifeedant activity against the carpet beetle (Attagenus japonicus ), a textile pest was also evaluated. While nordamnacanthal had strong antifeedant activity against the common cutworm, it did not show any antifeedant activity against the carpet beetle. The most effective antifeedant against the carpet beetle was the major constituent in the extract of R. trictorum, lucidin-3-O-primeveroside, a food pigment.     

Enzymic synthesis of o-succinylbenzoyl-CoA in cell-free extracts of anthraquinone producing Galium mollugo L. cell suspension cultures

o-Succinylbenzoic acid (OSB) is an intermediate in the biosynthesis of shikimatederived anthraquinones. The cell free activation of o-succinylbenzoic acid in extracts of anthraquinone producing cells of Galium mollugo L. is demonstrated for the first time. This activation depends on the presence of ATP, coenzyme A and Mg²⁺. The o-succinylbenzoic acid coenzyme A ester was identified by converting it to 1,4-dihydroxy-2-naphthoic acid by a bacterial enzyme, viz. naphthoatesynthase. It is thus demonstrated that the o-succinylbenzoic acid coenzyme A ester derived from bacteria and from Galium mollugo cells are identical.     

Uptake and Accumulation of {alpha}-Naphthalene Acetic Acid by Cell Suspensions of Galium mollugo L.

Fidgeon, C. and Wilson, G. 1988. Uptake and accumulation ofa-naphthalene acetic acid by cell suspensions of Galium mollugoL.—J. exp. Bot. 39: 241-249. Galium mollugo cell suspensions require -NAA for continued growthand cell division. The kinetics of -NAA uptake from the medium(B₅) by Galium cells was assessed using 1-¹⁴C -NAA in a standardratio of cells to medium (0.25 g: 2.5 cm³). It was found thatthe uptake of -NAA was rapid, over 90% being taken up within4 h. Cells which had accumulated -NAA for 4 h or more did notrelease it back into the medium. It was found that Galium cellsaccumulated -NAA against a significant concentration gradient;suggesting the participation of an active component in the uptakemechanism. The effect of free-space and surface adsorption onthe uptake of -NAA was determined by means of a repeated washtechnique. These two factors were found to be of importanceonly during the first hour of uptake. Neither dead cells norplasmolysed cells absorbed -NAA. It is clear that, in the normal growth cycle, Galium cells cantake up the available -NAA within 3 or 4 h of inoculation andthat this can stimulate a cell division response of 3-4 generationsover the subsequent 14 d. Key words: Galium, cell suspension, -naphthalene acetic acid     

In vitro antifungal and antibacterial activities of extracts of Galium tricornutum subsp. longipedunculatum

The aim of this study was to evaluate the antimicrobial activity of crude ethanolic extracts and fractions of the ariel parts and the fruits of Galium tricornutum subsp. longipedunculatum, traditionally used in northern areas of Pakistan for treating microbial infections of skin. Extracts and their fractions were tested against six bacteria and six fungal strains using the hole diffusion method and macrodilution method. All extracts and fractions possessed significant antimicrobial effect. Four fungal strains, Candida albicans, Trichophyton longifusus, Fusarium.solani and Candida glabrata, showed interesting susceptibility profiles when evaluated using the extracts and fractions with MICs ranging from 0.18 to 200 mg/mL. In case of bacterial strains, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi were significantly susceptible to the extracts and fractions with MICs ranging from 0.12 to 200 mg/mL. Comparative results were carried out using imepenem, miconazole and amphotericin B as standard antibiotics.     

Lysine221 is the general base residue of the isochorismate synthase from Pseudomonas aeruginosa (PchA) in a reaction that is diffusion limited

The isochorismate synthase from Pseudomonas aeruginosa (PchA) catalyzes the conversion of chorismate to isochorismate, which is subsequently converted by a second enzyme (PchB) to salicylate for incorporation into the salicylate-capped siderophore pyochelin. PchA is a member of the MST family of enzymes, which includes the structurally homologous isochorismate synthases from Escherichia coli (EntC and MenF) and salicylate synthases from Yersinia enterocolitica (Irp9) and Mycobacterium tuberculosis (MbtI). The latter enzymes generate isochorismate as an intermediate before generating salicylate and pyruvate. General acid–general base catalysis has been proposed for isochorismate synthesis in all five enzymes, but the residues required for the isomerization are a matter of debate, with both lysine221 and glutamate313 proposed as the general base (PchA numbering). This work includes a classical characterization of PchA with steady state kinetic analysis, solvent kinetic isotope effect analysis and by measuring the effect of viscosogens on catalysis. The results suggest that isochorismate production from chorismate by the MST enzymes is the result of general acid–general base catalysis with a lysine as the base and a glutamic acid as the acid, in reverse protonation states. Chemistry is determined to not be rate limiting, favoring the hypothesis of a conformational or binding step as the slow step.     

Isolation of microsatellite loci from the endangered plant Galium catalinense subspecies acrispum (Rubiaceae)

Galium catalinense subspecies acrispum (Rubiaceae) is a state‐endangered perennial shrub endemic to San Clemente Island. Eight polymorphic microsatellite loci were isolated from G. catalinense ssp. acrispum. These loci show high levels of variability, averaging 6.5 alleles per locus and an expected heterozygosity of 0.550. One locus exhibited significant deviations from Hardy–Weinberg equilibrium (P < 0.01) and one pair of loci exhibited significant linkage disequilibrium.     

The modification of phytosterol profiles and in vitro photosynthetic electron transport of Galium aparine L. (cleavers) treated with the fungicide, epoxiconazole

Foliar application of the triazole fungicide, epoxiconazole, retarded the growth of Galium aparine L. (cleavers). GC-MS and GC analysis clearly indicated that phytosterol biosynthesis in stem and leaflet tissue was significantly affected by this treatment. For example, in leaflet tissues, 125 g ai ha^-1 (field rate) caused reductions in campesterol and sitosterol of 81percnt; and 75percnt; respectively. C14-methyl phytosterols such as 14agr;-methylergost-8-enol, obtusifoliol and dihydroobtusifoliol were detected in treated tissues indicating that epoxiconazole inhibits the cytochrome P-450 dependent obtusifoliol 14agr;-demethylase. In addition, ratios of campesterol to sitosterol were reduced. Stigmasterol was not detected in control or treated tissues. Preliminary determination of photosynthetic characteristics of isolated thylakoids from treated plants indicated that electron transport and oxygen evolution were impaired by epoxiconazole and these effects were dose-related. Ten days after treatment, oxygen evolution from thylakoids (determined as electron flow from water to ferricyanide) isolated from control plants was 24.2 micro;mol mg^-1 chl h^-1, whilst treatment with 125 g and 250 g ai ha^-1 reduced this rate to 15.2 micro;mol and 8.2 micro;mol mg^-1 chl h^-1 an inhibition of 37 and 67percnt; respectively. These results suggest that epoxiconazole influences thylakoid integrity and function in addition to phytosterol biosynthesis in G. aparine.     

The plant growth regulator activity of the fungicide,epoxiconazole, on Galium aparine L. (cleavers)

The plant growth regulator activity of epoxiconazole, a new triazole fungicide, was investigated by time-course, dose-response and histology experiments with Galium aparine L. (cleavers). Seven days after treatment with 125g ai ha^–1 epoxiconazole (field rate), plant height was reduced by 43%. After seventeen days, leaflet area was reduced by 27% but leaflet fresh weight was not significantly influenced. This was partly because leaflet thickness had increased by 20% following epoxiconazole application. Chlorophyll concentrations were also increased on a unit area basis. Examination of leaflet anatomy showed that epoxiconazole elongated palisade, spongy mesophyll and upper epidermal cells. For example, 125g ai ha^–1 caused a 35% increase in the length of spongy mesophyll cells. Epoxiconazole also prevented cell separation as there were significantly more palisade and spongy mesophyll cells per unit area than in leaflets sprayed with water. Stem development was reduced and 125g ai ha^–1 inhibited the elongation of pith cells in stem tissue by 53%. However, the simultaneous application of gibberellin A₃ (GA₃) with epoxiconazole resulted in stem elongation similar to that of control plants. These observations are consistent with the expected effects following the inhibition of cytochrome P-450 dependent enzyme activity.Abbreviations GA₃ gibberellin A₃ - g ai ha^–1 grams of active ingredient per hectare - L ha^–1 litres per hectare - PPFD photosynthetic photon flux density - RH relative humidity - SE standard error     

Mechanical adaptations of cleavers (Galium aparine)

BACKGROUND AND AIMS: Cleavers (Galium aparine) is a fast-growing herbaceous annual with a semi-self-supporting, scrambling-ascending growth habit. Mature plants often use upright species for support. It is common in hedgerows and on waste ground. This study aims to characterize the mechanical behaviour of the stem and roots of cleavers and relate this to the arrangement of structural tissue, the net microfibrillar orientations in the cell walls, and plant growth habit. METHODS: The morphology and mechanics of mature cleavers was investigated using plants grown in pots and ones collected from the grounds at the University of Lincoln, Lincoln, UK. Tensile tests were carried out on the stem and the basal section of the first-order lateral roots. The net orientation of cellulose microfibrils in the cell walls was investigated using polarized light microscopy. KEY RESULTS: Results show that the basal regions of the stem and first-order lateral roots were highly extensible. Breaking strains of 24 +/- 7% were recorded for the stem base and 28 +/- 6% for the roots. Anatomical observations showed that the lower stem (base + 100 mm) was circular in cross-section with a solid central core of vascular tissue, whereas further up the stem the transverse section showed a typical four-angled shape with a ring-like arrangement of vascular tissue and sclerenchyma bundles in the corners. The net orientation of wall microfibrils in the secondary xylem diverges from the longitudinal by between 8 and 9 degrees . CONCLUSIONS: The basal region of the stem of cleavers is highly extensible, but the mechanism by which the stem is able to withstand such high breaking strains is unclear; reorientation of the cellulose fibrils in the stem along the axis of loading is not thought to be responsible.     

Infection Process of Plectosporium tabacinum on False Cleavers (Galium spurium)

A native fungus, Plectosporium tabacinum (van Beyma) M. E. Palm, W. Gams et Nirenberg, has potential as a bioherbicide for the control of both herbicide-resistant and herbicide-susceptible false cleavers. Limited information is available on the infection process of P. tabacinum. P. tabacinum spore distribution pattern, germination, penetration, and colonization on false cleavers leaves were examined using confocal, light, and scanning electron microscopy. The results demonstrated that conidia were distributed over the entire surface of leaves and cotyledons. More than 90% of the conidia germinated on the leaf surface 6-8 h after inoculation. Penetration of the leaf epidermis by conidia started 8-10 h after inoculation. Histological observation showed that no appressoria were formed by P. tabacinum, but its hyphae produced appressed club-like structures that penetrated the cuticle and epidermal layers. No stomata or other natural openings were observed on the upper leaf surface of false cleavers seedlings. Penetration occurs directly on epidermal cells with more frequent intercellular penetrations. Hyphal penetration was visualized at a depth of 30 and 40 üm after 8 and 16 h of incubation, respectively. Secondary hyphae colonized mesophyll cells 16 h after inoculation. Even spore distribution, short spore germination time, club-like infection structure formation, direct penetration, quick colonization, and mucous secretion on false cleavers leaves may contribute to the kill of false cleavers by P. tabacinum. Slow spore germination and germ tube growth, low spore germination numbers, and no infection structure formation on Brassica napus leaves may be factors affecting the host selectivity of P. tabacinum.     

耳草属(HedyotisL.)的起源及地理分布

依据耳草属的系统学,古地理学和细胞染色体资料分析和推论,耳草属植物的起源地点在冈瓦纳古陆,很可能在古陆辽阔的东北部地区。耳草属植物的起源时间不应晚于侏罗纪,有可能在三叠纪就已经出现,并在侏罗纪得到广泛的传播,其迁移的路线有四条,即从起源中心向东经上耳其,伊朗进入东南亚地区,向东南通过古南大陆向印度板块和徜大利亚扩散,向北进入北美地区,向西南进入南美洲地区,随着冈瓦纳古陆的分离,印度板块向北漂移以及澳大利亚与古南大陆的分离,植物迁移与扩散的速度受到了制约,耳草属植物现代分布格局形成的原因在于传播途径的隔断和第四纪冰川的作用。     

Purification of hydroxycinnamoyl-CoA:tyramine hydroxycinnamoyltransferase from cell-suspension cultures of Solanum tuberosum L. cv. Datura

A pathogen-elicitor-inducible acyltransferase [tyramine hydroxycinnamoyltransferase (THT); EC 2.3.1], which catalyzes the transfer of hydroxycinnamic acids from hydroxycinnamoyl-CoA esters to tyramine in the formation of N-hydroxycinnamoyltyramine, was purified to apparent homogeneity from cell-suspension cultures of potato (Solanum tuberosum L. cv. Datura), with a 1400-fold enrichment, a 5% recovery and a final specific activity of 208 mkat·(kg protein)^–1. Affinity chromatography on Reactive Yellow-3-Agarose using the acyl donor (feruloyl-CoA) as eluent was the decisive step in the purification sequence. The purified protein showed a native molecular mass of ca. 49 kDa. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis in the presence and in the absence of a reducing agent (2-mercaptoethanol) indicated that THT is a heterodimer in which the protein subunits (ca. 25 kDa) are non-covalently associated. The enzyme was stimulated fivefold by 10 mM Ca²⁺. The apparent K _m value for tyramine was dependent on the nature of the hydroxycinnamoyl-CoA present. Thus, the K _m value for tyramine was about tenfold greater (174 M) in the presence of 4-coumaroyl-CoA than in the presence of feruloyl-CoA (20 M).Abbreviations PAL phenylalanine ammonia-lyase - THT hydroxycinnamoyl-CoA:tyramine hydroxycinnamoyltransferase We thank the Deutsche Forschungsgemeinschaft and the Fonds der Chemischen Industrie for financial support. Further support by a grant from the Studienstiftung des Deutschen Volkes to H.H. is gratefully acknowledged.