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At least 19 recordsLinked to original sources

PubMed1985

Metabolism of Abscisic Acid in Guard Cells of Vicia faba L. and Commelina communis L.

Metabolism of abscisic acid (ABA) was investigated in isolated guard cells and in mesophyll tissue of Vicia faba L. and Commelina communis L. After incubation in buffer containing [G-(3)H]+/-ABA, the tissue was extracted by grinding and the metabolites separated by thin layer chromatography. Guard cells of Commelina metabolized ABA to phaseic acid (PA), dihydrophaseic acid (DPA), and alkali labile conjugates. Guard cells of Vicia formed only the conjugates. Mesophyll cells of Commelina accumulated DPA while mesophyll cells of Vicia accumulated PA. Controls showed that the observed metabolism was not due to extracellular enzyme contaminants nor to bacterial action.Metabolism of ABA in guard cells suggests a mechanism for removal of ABA, which causes stomatal closure of both species, from the stomatal complex. Conversion to metabolites which are inactive in stomatal regulation, within the cells controlling stomatal opening, might precede detectable changes in levels of ABA in bulk leaf tissue. The differences observed between Commelina and Vicia in metabolism of ABA in guard cells, and in the accumulation product in the mesophyll, may be related to differences in stomatal sensitivity to PA which have been reported for these species.

Journal Article↗

PubMed1999

alpha-Glucosidase inhibitors from Commelina communis.

A methanolic extract of Commelina communis showed potent inhibitory activity against alpha-glucosidase. One pyrrolidine alkaloid, 2,5-dihydroxymethyl-3,4-dihydroxypyrrolidine (DMDP, 1) and four piperidine alkaloids, 1-deoxymannojirimycin (2), 1-deoxynojirimycin (3), alpha-homonojirimycin (4) and 7-O-beta-D-glucopyranosyl alpha-homonojirimycin (5) were isolated by bioassay-directed fractionation and separation. These compounds have been identified for the first time from Commelina communis, supporting the pharmacological basis of this plant that has been used as a traditional herbal medicine for the treatment of diabetes.

Alkaloids↗

PubMed1990

Properties of Commelina yellow mottle virus's complete DNA sequence, genomic discontinuities and transcript suggest that it is a pararetrovirus.

The non-enveloped bacilliform viruses are the second group of plant viruses known to possess a genome consisting of circular double-stranded DNA. We have characterized the viral transcript and determined the complete sequence of the genome of Commelina mellow mottle virus (CoYMV), a member of this group. Analysis of the viral transcript indicates that the virus encodes a single terminally-redundant genome-length plus 120 nucleotide transcript. A fraction of the transcripts is polyadenylated, although the majority of the transcript is not polyadenylated. Analysis of the genome sequence indicates that the genome is 7489 bp in size and that the transcribed strand contains three open reading frames capable of encoding proteins of 23, 15 and 216 kd. The function of the 25 and 15 kd proteins is unknown. Similarities between the 216 kd polypeptide and the cauliflower mosaic virus coat protein and protease/reverse transcriptase polyprotein suggest that the 216 kd polypeptide is a polyprotein that is proteolytically processed to yield the virion coat protein, a protease, and replicase (reverse transcriptase and ribonuclease H). Each strand of the CoYMV genome is interrupted by site-specific discontinuities. The locations of the 5'-ends of these discontinuities, and the presence and location of a region on the CoYMV transcript capable of annealing with the 3'-end of cytosolic initiator methionine tRNA are consistent with replication by reverse transcription. We have demonstrated that a construct containing 1.3 CoYMV genomes is infective when introduced into Commelina diffusa, the host for CoYMV, using Agrobacterium-mediated infection.

Amino Acid Sequence↗

PubMed1998

Tubules containing virions are present in plant tissues infected with Commelina yellow mottle badnavirus.

Tubular structures containing bacilliform virions were observed in cell-free extracts of Commelina diffusa infected with Commelina yellow mottle badnavirus (CoYMV). The exterior of the tubule reacted with antibodies to CoYMV movement protein, but not with antibodies to virus coat protein. Similar tubular structures containing bacilliform particles were also observed in ultrathin sections of CoYMV-infected C. diffusa. These tubular structures traversed the cell wall at points where this was thickened or protruded. No similar structures were observed in healthy C. diffusa. These observations support the hypothesis that the virion-containing tubular structures observed in cell-free extracts are the same as those observed in situ, that these structures are composed, at least in part, of virus movement protein, and that they play a role in the cell-to-cell trafficking of virions of CoYMV.

Antibodies, Viral↗

PubMed1992

The Commelina yellow mottle virus promoter is a strong promoter in vascular and reproductive tissues.

Commelina yellow mottle virus (CoYMV) is a double-stranded DNA virus that infects the monocot Commelina diffusa. Although CoYMV and cauliflower mosaic virus (CaMV; another double-stranded DNA virus) probably replicate by a similar mechanism, the particle morphology and host range of CoYMV place it in a distinct group. We present evidence that a prompter fragment isolated from CoYMV confers a tissue-specific pattern of expression that is different from that conferred by the CaMV 35S promoter. When the CoYMV promoter is used to drive expression of the beta-glucuronidase reporter gene in stably transformed tobacco plants, beta-glucuronidase activity occurs primarily in the phloem, the phloem-associated cells, and the axial parenchyma of roots, stems, leaves, and flowers. Activity is also detected throughout the anther, with highest activity in the tapetum. In contrast, the CaMV 35S promoter is active in most cell types. The CoYMV promoter is a strong promoter, and when the activity of the CoYMV promoter is compared with that of a duplicated CaMV 35S promoter, it is 30% as active in tobacco suspension cells and up to 25% as active in maize suspension cells. These properties of the CoYMV promoter make it potentially useful for high-level expression of engineered genes in vascular cells.

Base Sequence↗

PubMed1994

Two Transduction Pathways Mediate Rapid Effects of Abscisic Acid in Commelina Guard Cells.

Commelina guard cells can be rapidly closed by abscisic acid (ABA), and it is thought that this signal is always transduced through increases in cytosolic calcium. However, when Commelina plants were grown at 10 to 17[deg]C, most guard cells failed to exhibit any ABA-induced increase in cytosolic calcium even though all of these cells closed. At growth temperatures of 25[deg]C or above, ABA-induced closure was always associated with an increase in cytosolic calcium. This suggests that there may be two transduction routes for ABA in guard cells; only one involves increases in cytosolic calcium. Activation of either pathway on its own appears to be sufficient to cause closure. Because the rates of ABA accumulation and transport in plants grown at different temperatures are likely to be different, we synthesized and microinjected caged ABA directly into guard cells. ABA was released internally by UV photolysis and subsequently caused stomatal closure. This result suggests a possible intracellular locale for the hypothesized ABA receptor.

Journal Article↗

PubMed2006

Stomatal movement in response to long distance-communicated signals initiated by heat shock in partial roots of Commelina communis L.

The systematic or long-distance signal transmission plays crucial roles in animal lives. Compared with animals, however, much less is known about the roles of long-distance signal communication in plant lives. Using the model plant Commelina communis L., we have probed the root to shoot communication mediated by heat-shock signals. The results showed that a heat shock of 5 min at 40 degrees C in partial roots, i.e. half or even 1/4 root system, could lead to a significant decrease in stomatal conductance. The regulation capability depends on both heat shock temperature and the amount of root system, i.e. with higher temperature and more roots stressed, the leaf conductance would decrease more significantly. Interestingly, the stomatal regulation by heat shock signal is in a manner of oscillation: when stomata conductance decreased to the lowest level within about 30 min, it would increase rapidly and sometimes even exceed the initial level, and after several cycles the stomata conductance would be finally stabilized at a lower level. Feeding xylem sap collected from heat-shocked plants could lead to a decrease in stomata conductance, suggesting that the heat shock-initiated signal is basically a positive signal. Further studies showed that heat shock was not able to affect ABA content in xylem sap, and also, not able to lead to a decrease in leaf water status, which suggested that the stomatal regulation was neither mediated by ABA nor by a hydraulic signal. Heat shock could lead to an increase in xylem sap H2O2 content, and moreover, the removal of H2O2 by catalase could partially recover the stomatal inhibition by xylem sap collected from heat-shocked plants, suggesting that H2O2 might be able to act as one of the root signals to control the stomatal movement. Due to the fact that heat-shock and drought are usually two concomitant stresses, the stomatal regulation by heat-shock signal should be of significance for plant response to stresses. The observation for the stomatal regulation in an oscillation manner by presently identified new signals should contribute to further understanding of the mystery for the pant systematic signaling in response to stresses.

Abscisic Acid↗

PubMed2004

Anti-hyperglycemic activity of Commelina communis L.: inhibition of alpha-glucosidase.

Since ages, botanical substances are in use for the remedy of diabetes with considerable degree of success. One of the such; an extract of Commelina communis L. (CE-L) after decoction in water has been traditionally used for the treatment of diabetes in Korea. However, its action mechanism has not yet been established. To explore the inside of its action-mechanism, in this study, the effect of the aqueous extract of C. communis L. (CE-L) on the activity of alpha-glucosidase was evaluated in vitro and in vivo. Aqueous extract of CE-L showed inhibitory activity of the alpha-glucosidase in a dose-dependent manner, in vitro. CE-L also seems to be by and large free from exerting any cytotoxic effect at least in CHO-K1 fibroblast and 3T3-L1 adipocyte. CE-L alleviated hyperglycemia caused by maltose or starch loading in normal and Streptozotocin (STZ)-induced diabetic mice with better efficacy than that of acarbose. In addition, prolonged administration of CE-L tends to normalize hyperglycemia in STZ-induced diabetic mice. Such results suggest that inhibitory activity of CE-L on alpha-glucosidase may contribute to delay in carbohydrate digestion and glucose absorption. Thus, CE-L has potential for use in the management of non-insulin-dependent diabetes.

Animals↗

PubMed2004

Biosynthesis of 1-deoxynojirimycin in Commelina communis: a difference between the microorganisms and plants.

1-Deoxynojirimycin is a glycosidase-inhibitory alkaloid obtained from several plants and microorganisms. Administration experiments using [1-(13C)] glucose in the higher plant Commelina communis and 13C NMR spectroscopic analyses of products suggested that 1-deoxynojirimycin was biosynthesized through a different route compared with that in Streptomyces and Bacilli microorganisms.

1-Deoxynojirimycin↗

PubMed2004

Total synthesis of flavocommelin, a component of the blue supramolecular pigment from Commelina communis, on the basis of direct 6-C-glycosylation of flavan.

We succeeded in a first total synthesis of flavocommelin (1), a component of the blue supramolecular pigment, commelinin (2), from Commelina communis, by direct 6-C-glycosylation of the flavan 4 using perbenzylglucosyl fluoride 8 in the presence of MS 5 angstroms in CH2Cl2 and a catalytic amount of BF3 x Et2O. After 6-C-glycosylation of 4, oxidation with CAN to flavanone 18 and subsequent 4'-O-glycosylation, promoted with a combination of BF3 x Et2O and DTBMP, afforded diglucosylflavanone 20. DDQ oxidation of 20 and deprotection successively gave 1.

Commelina↗

PubMed2004

Chemical interactions of Brachiaria plantaginea with Commelina bengalensis and Acanthospermum hispidum in soybean cropping systems.

Previous results obtained in soybean-wheat rotations under no-tillage conditions showed reductions in the seedbank of the weed species Commelina benghalensis, but no alteration in the seedbank of Acanthospermum hispidum in areas infested with Brachiaria plantaginea. Analyses of the soluble fraction of B. plantaginea indicated the predominance of aconitic acid (AA) among the aliphatic acids and ferulic acid (FA) among the phenolic acids. Laboratory bioassays using C. benghalensis and A. hispidum were carried out to evaluate phytotoxic effects of pure organic acid solutions and dilute extracts of B. plantaginea on seed germination, root development, and fungal germination. Solutions of AA and FA were prepared at 0.25, 0.50, and 1.0 mM. Extracts of B. plantaginea were diluted to obtain concentrations of AA similar to those in the prepared solutions. Seeds were sown on 0.5% agar (containing AA, FA, or diluted extract) in plastic-covered receptacles and maintained in a germination chamber for 10 days. AA and FA solutions and the B. plantaginea extract reduced germination and root length, mainly of C. benghalensis. AA also stimulated the development of endophytic fungi (Fusarium solani), which had complementary adverse effects on C. benghalensis germination. FA and AA may play important roles in reducing the seedbank of some weed species, acting directly on germination and development and, indirectly, by stimulating endophytic fungi that alter germination.

Aconitic Acid↗

PubMed2005

Comparative structure and pollen production of the stamens and pollinator-deceptive staminodes of Commelina coelestis and C. dianthifolia (Commelinaceae).

BACKGROUND AND AIMS: Flowers of Commelina coelestis and C. dianthifolia provide pollen alone as a floral reward, and rely on visual cues to attract pollinators. Three stamen types, all producing pollen, occur in each of these species: two cryptically coloured lateral stamens, a single cryptically coloured central stamen and three bright yellow staminodes that sharply contrast with the blue to purple corolla. The objective was to compare the stamen structure and pollen characteristics of each of the three stamen types, and to test the hypothesis that the staminodes are poor contributors of viable pollen for the siring of seed. The pollination roles of the three stamen types and the breeding systems of both species were also explored. METHODS: Light, fluorescence and scanning electron microscopy were utilized to examine stamen morphology and pollen structure and viability. Controlled hand pollinations were used to explore the breeding system of each species. Filament and style lengths were measured to investigate herkogamy and autogamy. KEY RESULTS: Pollen from all stamen morphs is viable, but staminode pollen has significantly lower viability. Pollen polymorphism exists both (a) between the lateral and central stamens and the staminodes, and (b) within each anther. Lateral and central stamens have thicker endothecia with a greater number of secondary cell wall thickenings than the staminodes. CONCLUSIONS: Both species are entomophilous and facultatively autogamous. Lateral stamen pollen is important for cross-pollination, central stamen pollen is utilized by both species as a pollinator reward and for delayed autogamy in C. dianthifolia, and the staminodes mimic, by means of both colour and epidermal features, large amounts of pollen to attract insects to the flowers. Pollen from all three anther morphs is capable of siring seed, although staminode pollen is inferior. The thin staminode endothecium with fewer secondary thickenings retards staminode dehiscence.

Commelina↗

PubMed1996

The ORF I and II proteins of Commelina yellow mottle virus are virion-associated.

Antibodies were prepared against bacterially expressed Commelina yellow mottle badnavirus (CoYMV) proteins. Antiserum against purified virions and antiserum against the C-terminus of the putative coat protein-encoding region of ORF III detected the same virus-specific proteins, indicating that the CoYMV coat protein is encoded in ORF III. In addition to the two major forms of the coat protein (37 and 39 kDa), several high molecular weight virus-specific proteins were detected when virions were isolated without chloroform treatment. These proteins are possible ORF III polyprotein processing intermediates and might be associated with "immature" virions which are eliminated by chloroform treatment. As predicted by the genomic sequence, a 20-kDa virus-specific protein was detected by an antiserum raised against the C-terminus of the putative ORF I protein. Results of filtration experiments suggest that the ORF I protein is equally associated with virions and with plant component(s). The association between the ORF I protein and the virions was further confirmed using immunosorbent electron microscopy and immunogold labeling. The ORF I protein was not detected in virus preparations treated with chloroform, and colocalized with virions containing immature coat protein on sucrose-cesium sulfate density gradients, suggesting that it is associated with immature virions. An antiserum raised against the putative ORF II gene product detected a 15-kDa virus-specific protein whose association with the virions was unaffected by chloroform treatment. The ORF II protein was found to be sensitive to some protease(s) that copurified with the virions, and protease inhibitors preventing this degradation have been identified.

Bacterial Proteins↗

PubMed1997

The N-terminal portion of the 216-kDa polyprotein of Commelina yellow mottle badnavirus is required for virus movement but not for replication.

Commelina yellow mottle virus (CoYMV) is the type member of the badnaviruses, a genus of plant pararetroviruses. The N-terminus of the polyprotein encoded by ORF III has limited similarity to known cell-to-cell movement proteins. To test the hypothesis that the N-terminus is required for viral movement, the phenotypes caused by mutations constructed in this region were determined. Similar to mutants affected in the reverse transcriptase, mutants affected in the putative movement protein were unable to cause a systemic infection. However, when the abilities of the mutated viral genomes to direct virion assembly and replication were tested using an in vitro stem-culture system, the mutants affected in the putative movement protein were found to assemble virions, whereas the reverse transcriptase mutants were unable to do so. Moreover, the putative movement protein mutants were shown to be replication competent by detection and mapping of one of the genomic discontinuities that are the hallmark of replication by reverse transcription. Thus the N-terminal region of ORF III is required for the systemic movement but not for the replication of CoYMV.

Badnavirus↗

PubMed2002

The Commelina yellow mottle virus promoter drives companion-cell-specific gene expression in multiple organs of transgenic tobacco.

Previous work has demonstrated that some endogenous plant gene promoters are active in selective companion cells of the phloem, depending on organ types and developmental stages. Here we report that the Commelina yellow mottle virus (CoYMV) promoter is active in the companion cells of leaves, stems and roots of transgenic Nicotiana tabacum cv. Xanthi NN, using beta-glucuronidase (GUS) as a reporter. Thus, the CoYMV promoter has a broad organ specificity. This promoter can be useful in molecular studies on the functions of companion cells in many aspects of phloem biology, such as regulation of long-distance transport, macromolecular traffic, plant development and interaction with pathogens. It may also be useful in engineering crops that produce specific gene products in the companion cells to block long-distance movement of pathogens.

Gene Expression Regulation, Plant↗

PubMed1991

Characterization of the genome of rice tungro bacilliform virus: comparison with Commelina yellow mottle virus and caulimoviruses.

Rice tungro disease is caused by an infection of two different viruses, rice tungro spherical virus (a (+) sense RNA virus) and rice tungro bacilliform virus (RTBV) with a genome of circular double-stranded DNA. The genome of an RTBV isolate from the Philippines was cloned, sequenced, and found to be 8000 bp in length. It contains four open reading frames (ORFs) on a single strand, with ORF 1 having an internal termination codon (TAA). The 5' and 3' ends of a polyadenylated viral RNA transcript, of genome length, were mapped by primer extension and cDNA sequence analysis, respectively. The transcript is terminally redundant by 265-268 nucleotides. Purified virus particles contain two major proteins with molecular masses of 37 and 33 kDa, although only the 37-kDa protein was detected in the infected rice tissues. The N-terminal amino acid sequence of the 33-kDa protein was determined and its coding region was identified on the RTBV genome. The identity of the coat protein gene was further confirmed by expressing a region of the genome in Escherichia coli, the products of which reacted with anti-RTBV antibody. The unusually long ORF 3 of RTBV is predicted to encode a polyprotein of 194.1 kDa that includes: the coat protein(s), viral proteinase, reverse transcriptase, and ribonuclease H. The sections of the polyprotein show varying degrees of similarity to the counterparts of Commelina yellow mottle virus (a member of the proposed badnavirus group) and caulimoviruses. The functions of the other three ORFs are unknown.

Amino Acid Sequence↗

PubMed2001

Pharmacological evidence for the implication of both cyclic GMP-dependent and -independent transduction pathways within auxin-induced stomatal opening in Commelina communis (L.).

It has been previously suggested that auxin-induced stomatal opening results from at least two transduction pathways, one of which involves cyclic GMP (cGMP) as the mediator within a Ca(2+) signalling cascade. This hypothesis was investigated further in epidermal peels of Commelina communis by comparing the effects of potential inhibitors of plant Ca(2+)-dependent enzymes on the stomatal opening responses to the auxin indolyl-3-butyric acid (IBA) and to the cGMP membrane-permeable derivative 8-bromoguanosine 3',5'-cyclic monophosphate (8-Br-cGMP). In the 30-50 &mgr;M range, the potential plant calmodulin (CaM) antagonist N-(aminohexyl)-5-chloro-1-naphthalenesulphonamide (W-7) positively interacted with IBA but not with 8-Br-cGMP to open the stomata. The CaM antagonists W-7 (in the 10-20 &mgr;M range) and N-(aminohexyl)-1-naphthalenesulphonamide (40 &mgr;M), the potential inhibitors of plant protein kinases 1-(5-isoquinolinylsulfonyl)-2-methylpiperazine (20 and 200 &mgr;M) and K-252a (0.6 &mgr;M), and cyclosporine A and FK506, potential inhibitors of plant homologs of Ca(2+)-CaM complex (Ca(2+)/CaM)-dependent protein phosphatase 2B, prevented the IBA and 8-Br-cGMP responses by about 70% and 100%, respectively. Together, these results provide indirect pharmacological evidence that, in addition to the cGMP-dependent pathway, the auxin signal is transduced through at least one cGMP-independent pathway.

Journal Article↗

PubMed1998

Antidiarrhoeal activity of Waltheria americana, Commelina coelestis and Alternanthera repens.

The antidiarrhoeal activity of the hexane, chloroform, methanol and aqueous extracts of Waltheria americana, Commelina coelestis and Alternathera repens, was tested on mice with diarrhoea induced by castor oil and MgSO4. The methanol extract of C. coelestis and A. repens and aqueous extract of A. repens, presented antidiarrhoeal effect, monitored by number of liquid feces defecated and intestinal transit of a suspension of graphite with castor oil in Wistar rats.

Administration, Oral↗