Three new neolignan glucosides from the stems of Dendrobium aurantiacum var. denneanum

Three new neolignan glucosides (1–3), together with four known analogs (4–7), have been isolated from the stems of Dendrobium aurantiacum var. denneanum. Structures of the new compounds including the absolute configurations were determined by spectroscopic and chemical methods as (−)-(8R,7′E)-4-hydroxy-3,3′,5,5′-tetramethoxy-8,4′-oxyneolign-7′-ene-9,9′-diol 4,9-bis-O-β-d-glucopyranoside (1), (−)-(8S,7′E)-4-hydroxy-3,3′,5,5′-tetramethoxy-8,4′-oxyneolign-7′-ene-9,9′-diol 4,9-bis-O-β-d-glucopyranoside (2), and (−)-(8R,7′E)-4-hydroxy-3,3′,5,5′,9′-pentamethoxy-8,4′-oxyneolign-7′-ene-9-ol 4,9-bis-O-β-d-glucopyranoside (3), respectively.     

Accumulation of scopoletin is associated with the high disease resistance of the hybrid Nicotiana glutinosa x Nicotiana debneyi

The high disease resistance of the amphidiploid hybrid of Nicotiana glutinosa x Nicotiana debneyi is associated with high constitutive levels of two phenolic compounds as analysed by high-performance liquid chromatography. The structures of these two compounds were elucidated by means of gas chromatography-tandem mass spectrometry, fluorescence- and light-spectrophotometry to be those of scopolin and scopoletin. They reached levels of 4 nmol·(g FW)^?1 and 35 nmol·(g FW)^?1, respectively, in leaf tissues of the hybrid, about 10–50 times the amount found in the parental species. Scopoletin showed a direct antimicrobial activity against Cercospora nicotianae, Phytophthora parasitica var. nicotianae, Pseudomonas syringae pvs. tabaci and syringae and tobacco mosaic virus when added to synthetic growth media, mixed with the inoculum or sprayed onto tobacco plants prior to inoculation. We postulate that the high amount of toxic phenolics in the leaves of the hybrid N. glutinosa x N. debneyi contributes to its high disease resistance.     

Molecular systematics and phytochemistry of Rehmannia (Scrophulariaceae)

The relationships between the six known species of Rehmannia were investigated. With regard to the content of iridoid glucosides, caffeoyl phenylethanoid glycosides (CPGs) and ionone glucosides, no conclusions could be drawn. Phylogenetic analysis of DNA sequence data (ITS region, trnL-F region and rps16 intron) reveal a well-resolved topology in which Rehmannia glutinosa and Rehmannia solanifolia and Rehmannia piasezkii and Rehmannia elata are well-supported species pairs. Rehmannia chingii is sister to the rest of the genus, which is congruent with its distribution distant to the other species of the genus.     

A general method for the high-yield isolation of mesophyll protoplasts from deciduous tree species

High yields (1.2–8.0 × 10⁶ g fresh wt.^?1) of viable leaf mesophyll protoplasts have been isolated from a range of mature deciduous woody-plant species (Betula pendula, Alnus glutinosa, Salix caprea var. Kuroyanagi, S. alba var. Tristis, Populus Tacatricho (= P. tacamahacca × trichocarpa 32), Ulmus glabra var. camperdown), and juvenile glasshouse-grown material (B. pendula, B. pubescens, A. glutinosa). Protoplasts are only released if chopped leaf tissue is thoroughly washed prior to digestive enzyme addition. The nature of the washing requirement has been investigated and it has been demonstrated that water soluble compounds are released from chopped leaves which modify their cell-wall structure rendering them resistant to enzymic digestion. When analyzed by paper chromatography the leachate from B. pendula leaves was found to contain the hydroxycinnamic acids p-coumaric acid (PCA) and o-coumaric acid (OCA). Pre-incubation of B. pendula tissue (which is normally susceptible to enzymic digestion) in authentic samples of PCA and OCA prior to enzymic incubation, completely suppressed protoplast yields. The relevance of hydroxycinnamic acids to protoplast isolation and plant tissue culture is discussed.     

Secretion of catalpol from Rehmannia glutinosa roots to the rhizosphere

The concentrations of catalpol in the culture solutions, roots, stems and leaves of Rehmannia glutinosa Libosch. were determined by HPLC. The biological activity of catalpol was detected with Arabidopsis thaliana L. seedlings. The results showed that all R. glutinosa Libosch. vegetative organs contained catalpol. Catalpol was also found in culture solutions in which the R. glutinosa Libosch. seedlings were grown. Catalpol inhibited seed germination and root growth in A. thaliana L., respectively, at concentration 80 and 20 μmol/dm³. These results suggest that R. glutinosa Libosch. may produce catalpol and secrete it into the culture solutions. Catalpol acts as an antimicrobial and allelopathic agent; the secretion of catalpol into the R. glutinosa Libosch. rhizosphere may provide a competitive advantage for root establishment through local suppression of soil microorganisms and inhibition of the growth of competing plant species. However, autotoxicity of catalpol in R. glutinosa Libosch. may occur, which may be relevant to the obstacle in its continuous cropping.     

Compensation for a Mutated Auxin Biosynthesis Gene of Agrobacterium Ti Plasmid A66 in Nicotiana glutinosa Does Not Result from Increased Auxin Accumulation

Nicotiana glutinosa compensated for a mutated tumor-morphology-shooty (tms) (auxin biosynthesis) locus of Agrobacterlum tumefaciens strain A66 and showed the same virulent tumor response to infection by strain A66 or the wild-type strain A6. Cloned cell lines transformed by strains A6 or A66 were fully hormone independent in culture and grew rapidly as friable, unorganized tissues on hormone-free growth medium. Growth of N. glutinosa tumor cells was inhibited by addition of α-naphthaleneacetic acid to the growth medium, and A6- and A66-transformed cells showed similar dose responses to this auxin. On the other hand, A6-transformed cells contained much higher levels of indole-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylic acid (ACC) than A66-transformed cells. Differences in IAA and ACC levels in N. glutinosa tumor lines were consistent with the expected activity of the tms locus and were quantitatively similar to results obtained previously with A6- and A66-transformed cells of Nicotiana tabacum, which does not compensate for mutated tms genes. Thus, compensation for mutated tms genes in N. glutinosa did not result from increased auxin accumulation and did not appear to be related to the capacity of this host for auxin biosynthesis.     

Intermediacy of iridodial in the biosynthesis of some iridoid glucosides

Administration of MVA-[2-¹⁴C] to Lamium applexicaule and Deutzia crenata as well as of 11-hydroxyiridodial glucoside-[10-³H] and 7-deoxyloganic acid-[10-³H] to the former plant suggested that, in contrast to secoiridoid-indole alkaloids, iridoid glucosides such as ipolamiide, lamiide, lamioside, deutzioside and scabroside in these plants are biosynthesized via iridodial. Iridodial as a precursor for the biosynthesis of asperuloside was also suggested from the results of the administration of MVA-[2-¹⁴C] to Galium spurium var. echinospermon.     

Sesquiterpenoid stress compounds from Nicotiana species

Solavetivone, 3-hydroxysolavetivone, solanascone, phytuberin and phytuberol were identified as stress compounds in leaves of Nicotiana tabacum cv Samsun NN. N. sylvestris, which is the maternal progenitor of N. tabacum, produced all the above compounds except 3-hydroxysolavetivone. In the F₁, hybrid of N. tabacum and N. glutinosa, all the stress compounds produced by N. tabacum and N. glutinosa, respectively, were accumulated.     

Selective Somatic Elimination of NICOTIANA GLUTINOSA Chromosomes in the F(1) Hybrids of N. SUAVEOLENS and N. GLUTINOSA

The F₁ hybrids of Nicotiana suaveolens (subgenus Petunioides, 2n = 32) and N. glutinosa (subgenus Tabacum, 2n = 24), were examined during their development, from seedlings to mature plants. It was observed that in the hybrids, there was a progressive change of dominant N. glutinosa morphological characteristics towards those of N. suaveolens, in leaf shape, stem, flower color and branching pattern. A study of mitotic chromosomes in the root-tips and in very young anthers of the mature plants indicated a significantly high average frequency of aberrant mitotic anaphases (bridges and fragments, 12% and 11% respectively). As a consequence of this phenomenon, variability in the number and size of chromosomes was observed in the PMC's and in mitotic metaphases (29-24 chromosomes). In order to establish whether the N. glutinosa chromosomes were preferentially lost, a karyological study of the parents and their F₁ hybrids was carried out and it was established that the F₁ hybrids were losing N. glutinosa chromosomes preferentially. A mechanism was suggested for the loss of these chromosomes by means of a chromatid type of breakage-fusion-bridge cycle (b-f-b cycle) and initiation of the b-f-b cycle in the hybrid due to an interaction of the regulatory mechanism of DNA replication in the haploid genomes of the parental species. However, loss of these chromosomes owing to interaction of certain genes from the two parental species cannot be ruled out.     

Ineffective Frankia and host resistance in natural populations of Alnus glutinosa (L.) gaertn

Alnus glutinosa (black alder) populations are known to exhibit a variable degree of incompatibility to root nodule formation by ineffective Frankia. The relationship between the occurrence of ineffective Frankia in wet stands of black alder and the degree of resistance to nodulation by ineffective Frankia of seed-lots and clones of alder trees from these particular locations was studied through soil inoculation experiments. The average percentage of resistant plants (R-frequency) among the seed-lots from locations with an ineffective Frankia soil population was equal to, or higher than, the R-frequencies of locations without ineffective Frankia. The mean R-frequency was highest for the seed-lots from the location from which the soil inoculant was taken. These results strongly suggest that ineffective Frankia are not strictly dependent on susceptible A. glutinosa for the maintenance of their population size. The fungus Penicillium nodositatum also nodulated A. glutinosa seedlings. Whereas a negative interaction with the ineffective Frankia nodulation was found, this did not have a significant effect on the R-frequencies of the seed-lots that were tested, suggesting that the ineffective Frankia nodulation adversely affected the myco-nodulation, and not vice versa.     

P-hydroxyacetophenone derivatives from Artemisia Campestris ssp. Glutinosa

The weakly acidic fraction from Artemisia campestris ssp. glutinosa contains five p-hydroxyacetophenone derivatives, which are structurally biogenetically related.     

Rehmannia inhibits adipocyte differentiation and adipogenesis

Rehmannia glutinosa, a Traditional Chinese Medicine (TCM), has been used to increase physical strength. Here, we report that Rehmannia glutinosa extract (RE) inhibits adipocyte differentiation and adipogenesis. RE impairs differentiation of 3T3-L1 preadipocytes in a dose-dependent manner. At the molecular level, treatment with RE inhibits expression of the key adipocyte differentiation regulator C/EBPβ, as well as C/EBPα and the terminal marker protein 422/aP2, during differentiation of preadipocytes into adipocytes. Additionally, RE inhibits the mitotic clonal expansion (MCE) process of adipocyte differentiation, and RE prevents localization of C/EBPβ to the centromeres. RE also prevents high fat diet (HFD) induced weight gain and adiposity in rats. Taken together, our results indicate that Rehmannia glutinosa extract inhibits preadipocyte differentiation and adipogenesis in cultured cells and in rodent models of obesity.     

Aromatic compounds from Artemisia campestris subsp. Glutinosa

From the weakly acid fraction of the hexane extract from Artemisia campestris subsp. glutinosa, five new aromatics have been isolated. They hav     

2-Methyl-2-hydroxymethylchromenes from Artemisia campestris subsp. glutinosa

From the non volatile neutral part of a hexane extract from Artemisia campestris subsp. glutinosa, two new 2-methyl-2-hydroxymethyl chromenes h     

Effect of tobacco mosaic virus infection of levels of soluble superoxide dismutase (SOD) in nicotiana tabacum and nicotiana glutinosa leaves

The activity of superoxide dismutase (SOD: E.C. 1.15.1.1) was evaluated on Nicotiana tabacum and Nicotiana glutinosa leaf tissue after Tobacco Mosaic Virus (TMV) infection. Significant increase in extracted SOD appeared to be directly related to the appearance of necrotic and systemic symptoms in hypersensitive (N. glutinosa and N. tabacum cv. Havana 425) and susceptible (N. tabacum cv. Bright BC 60) leaves, respectively. SOD activity did not change significantly during the replication of TMV in the inoculated susceptible leaves up to 4 days after inoculation. Both cyanide-insensitive (2 days after inoculation) and sensitive (3–4 days after inoculation) enzymes increased during the expression of the hypersensitivity. Only cyanide-sensitive enzyme increased in systematically infected leaves. SOD and peroxidase increased simultaneously and the enhancement of peroxidase was higher than that of SOD. The values of peroxidase greatly exceeded that of SOD only in the hypersensitive leaves during local lesion differentiation. In N. tabacum leaves 4 clear SOD bands were separated by polyacrylamide gel electrophoresis: 3 cyanide-sensitive (Cu,Zn enzyme) and 1 cyanide-insensitive, while N. glutinosa had 3 bands: 2 cyanide-sensitive and 1 cyanide-insensitive. The cyanide-insensitive band, both in N. tabacum and N. glutinosa, was sensitive to H₂O₂ and insensitive to chloroform-ethanol treatment and thus supposed to be Fe enzyme. The infection did not induce change in the electrophoretic pattern of SOD enzymes.In summary, our results indicate that the pathogenic alteration caused by TMV infection both in the compatible and in the incompatible combinations are characterized by an induction of SOD activity, particularly cyanide-sensitive Cu,Zn-SOD. The connection between the induction of SOD and a possible activation of O₂⁻ production in the hypersensitive tissue following TMV infection is discussed.