Shoot differentiation from protocorm callus cultures of Vanilla planifolia (Orchidaceae): proteomic and metabolic responses at early stage

<p>Abstract</p> <p>Background</p> <p><it>Vanilla planifolia </it>is an important Orchid commercially cultivated for the production of natural vanilla flavour. Vanilla plants are conventionally propagated by stem cuttings and thus causing injury to the mother plants. Regeneration and <it>in vitro </it>mass multiplication are proposed as an alternative to minimize damage to mother plants. Because mass production of <it>V. planifolia </it>through indirect shoot differentiation from callus culture is rare and may be a successful use of in <it>vitro </it>techniques for producing somaclonal variants, we have established a novel protocol for the regeneration of vanilla plants and investigated the initial biochemical and molecular mechanisms that trigger shoot organogenesis from embryogenic/organogenic callus.</p> <p>Results</p> <p>For embryogenic callus induction, seeds obtained from 7-month-old green pods of <it>V. planifolia </it>were inoculated on MS basal medium (BM) containing TDZ (0.5 mg l^-1). Germination of unorganized mass callus such as protocorm -like structure (PLS) arising from each seed has been observed. The primary embryogenic calli have been formed after transferring on BM containing IAA (0.5 mg l^-1) and TDZ (0.5 mg l^-1). These calli were maintained by subculturing on BM containing IAA (0.5 mg l^-1) and TDZ (0.3 mg l^-1) during 6 months and formed embryogenic/organogenic calli. Histological analysis showed that shoot organogenesis was induced between 15 and 20 days after embryogenic/organogenic calli were transferred onto MS basal medium with NAA (0.5 mg l^-1). By associating proteomics and metabolomics analyses, the biochemical and molecular markers responsible for shoot induction have been studied in 15-day-old calli at the stage where no differentiating part was visible on organogenic calli. Two-dimensional electrophoresis followed by matrix-assisted laser desorption ionization time-of-flight-tandem mass spectrometry (MALDI-TOF-TOF-MS) analysis revealed that 15 protein spots are significantly expressed (<it>P </it>< 0.05) at earlier stages of shoot differentiation. The majority of these proteins are involved in amino acid-protein metabolism and photosynthetic activity. In accordance with proteomic analysis, metabolic profiling using 1D and 2D NMR techniques showed the importance of numerous compounds related with sugar mobilization and nitrogen metabolism. NMR analysis techniques also allowed the identification of some secondary metabolites such as phenolic compounds whose accumulation was enhanced during shoot differentiation.</p> <p>Conclusion</p> <p>The subculture of embryogenic/organogenic calli onto shoot differentiation medium triggers the stimulation of cell metabolism principally at three levels namely (i) initiation of photosynthesis, glycolysis and phenolic compounds synthesis; (ii) amino acid - protein synthesis, and protein stabilization; (iii) sugar degradation. These biochemical mechanisms associated with the initiation of shoot formation during protocorm - like body (PLB) organogenesis could be coordinated by the removal of TDZ in callus maintenance medium. These results might contribute to elucidate the complex mechanism that leads to vanilla callus differentiation and subsequent shoot formation into PLB organogenesis. Moreover, our results highlight an early intermediate metabolic event in vanillin biosynthetic pathway with respect to secondary metabolism. Indeed, for the first time in vanilla tissue culture, phenolic compounds such as glucoside A and glucoside B were identified. The degradation of these compounds in specialized tissue (i.e. young green beans) probably contributes to the biosynthesis of glucovanillin, the parent compound of vanillin.</p

Effect of Light and Cytokinins on Secondary Metabolism in Cell Suspensions of Psiadia arguta (Pers.) Voigt.

The production of secondary metabolites from cell suspensions of P. arguta, an endangered endemic plant from  Mauritius has never been reported. In order to identity the optimum culture conditions, the effect of light and cytokinins on phenylpropanoid products was studied. These conditions were, exposure of cells to a 16hr photoperiod and culture in MS basic medium containing TDZ (2mg/l) +NAA (0.5mg/l). Under such conditions, the production of tannins and flavonoids was higher than observed in crude leaf extracts. These data show that TDZ, like in any morphogenic process, acts as a powerful cytokinin enhancing the phenylpropanoid pathway. Nevertheless, TDZ activity seems to be contradictory with respect to the production of 2-phenyl-4-H-1- benzopyran-4-one and tannic acid as opposed to 1,2 benzopyrone synthesis.Keywords: Psiadia arguta (Pers.)Voigt, Asteraceae, phenylpropanoid, 1,2- benzopyrone, 2-phenyl- 4-1-benzopyran-4-one, tannic acid, phenol, PAL, TDZ, BAP

Seasonal occurrences of Manta birostris (Chondrichthyes: Mobulidae) in southeastern Brazil

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)An analysis of 79 underwater photographs of Manta birostris gathered over a period of nine years in a marine protected area in southeastern Brazil suggests a high predictability of manta ray occurrences in the region during the austral winter (June-September). The reasons for this are probably related to the seasonal oceanographic conditions, as characterized by the presence of a coastal front at the study site in winter and consequent plankton enrichment, which provides a feeding opportunity for manta rays. In addition, a melanistic individual in the Atlantic Ocean that is similar in color to the Pacific Ocean's "black manta" is reported for the first time.5619699Fotoidentificacao e sazonalidade da raia manta (Manta birostris) no Parque Estadual Marinho da Laje de Santos [COTEC-42.637/2006]Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fotoidentificacao e sazonalidade da raia manta (Manta birostris) no Parque Estadual Marinho da Laje de Santos [COTEC-42.637/2006]CNPq [135112/2007-9

Comparison between Solanum torvum Sw. and S. melongena L. after Ralstonia solanacearum inoculation

Bacterial wilt, caused by Ralstonia solanacearum, is one of the most devastating plant diseases, affecting some economically important Solanaceae crops. In contrast, Solanum torvum, also known as wild eggplant, does not wilt when infested with R. solanacearum. In order to describe the mechanism underlying the response of S. torvum, it was compared with the cultivated eggplant, S. melongena, when both were infected with the same R. solanacearum strain. No wilting occurred in S. torvum, although the bacteria colonised roots and stems in both species within the first 24 h. There were marked differences beyond 24 h, consisting of high bacterial mortality in S. torvum. Using the calli model, our investigations revealed an increase in cell wall monoamine oxidase activity in S. torvum after R. solanacearum inoculation, which did not occur in S. melongena

DNA AND ANTIMICROBIAL FINGERPRINTING OF MEDICINAL ALOE SPECIES FROM THE MASCARENE ISLANDS

Antimicrobial and molecular studies of two endemic medicinal plants from Mauritius L. tomentorii and L. purpureum and Lomatophyllum macrum from Reunion Island was done to differentiate them from Aloe vera which belongs to the same family Asphodelaceae. These endemic Aloes are used in the Mauritian and Reunion pharmacopoeia to treat bacterial infections and as antispasmodic.3 Phytochemical screening of the crude extracts revealed the common presence of alkaloids, anthraquinones, coumarins, phenols, saponins and tannins. Anthraquinones and saponins had also been reported as bioactive compounds present in Alooideae and in Aloe vera 1,4 .Antimicrobial activity was tested against Escherichia coli, Klebsiella pneumoniae and Staphylococcus aureus using the microplate dilution method. Extracts of Lomatophyllum species showed more potent antimicrobial activity than Aloe vera with MIC ranging 0.003-0.006mg/L as compared to 0.012-.0.028mg/L for Aloe vera.The antimicrobial properties of L. tormentorii and L. purpureum were attributed to the presence of alkaloids, coumarins, and saponins which are known to possess antimicrobial attributes. In this study we also make use of a modified RAPD-PCR technique. to elucidate the genetic closeness of Lomatophyllum to Aloe. Genomic DNA was extracted using a modification of the method used by Govinden-Soulange et al (2007)2. RAPD-PCR technique has revealed that Lomatophyllum species and Aloe vera share some genetic similarities. Consequently we report the genetic diversity of the Lomatophyllum species by measuring the genetic distance, which they have with Aloe vera. Moreover some biologically active compounds within the Lomatophyllum are established and their possible similarities with Aloe vera are unveiled. Key Words: Biological activities, Lomatophyllum, Aloes, genetic distance References: 1. Atherton, P. (1999). Aloe vera: myth or medicine? Positive Health, 20 June/July. 2. Govinden-Soulange J, Ranghoo-Sanmukhiya M, Seeburrun SD. (2007). Tissue culture and RAPD analysis of Cinnamomum camphora and Cinnamomum verum. Biotechnology. 6(2):239-244 3. Gurib-Fakim, A. Gueho, J., Sewraj, M. and Dulloo, E. (1994). Plantes Medicinales de l’Ile Rodrigues. Editions de l’Ocean Indien, Maurice. 4. Mark, W.C., Anette, Y.D., Anthony, V.C., Gail, R., Paula, J.R. Margaret, A.T. and Lui, E.E. (2000). Phylogenetics of Asphodelaceae (Asparagales): Analysis of Plastid rbcL and trn-L-F DNA Sequences. Annals of Botany, 86: 935-951

Evidence of parietal amine oxidase activity in Solanum torvum Sw. stem calli after Ralstonia solanacearum inoculation

Calli induced from Solanum torvum stem explants were inoculated with Ralstonia solanacearum under partial vacuum. All calli showed a hypersensitive response after infiltration. Furthermore, amine oxidase activity with aldehyde and H2O2 production was detected in semi-purified cell walls of calli infiltrated by the bacteria. Due to its preferential affinity for monoamines, this enzyme is supposed to have monoamine oxidase-like (MAO-like) activity. Moreover, the presence of hydroxyl radicals in the aromatic cycle alters the oxidative deamination kinetics of potential substrates. Indeed, the oxidation of dopamine (+2, OH) was shown to be faster than that of tyramine (+1, OH), which in turn was faster than that of phenylethylamine (0, OH). The MAO-like catalytic activity was significantly inhibited by some reducing agents such as sodium bisulphite and cysteine, and also by tryptamine under anaerobiosis. This latter result suggested that the prosthetic group of the MAO-like enzyme could be a tyrosine-derived 6-hydroxytopaquinone structure. Finally, the sigmoid kinetics of the MAO-like enzyme in semi-purified cell walls did not correspond to that expected for a purified MAO, suggesting that the kinetics were affected by some factors present in cell walls

Gouvernance Adaptative Des Catastrophes D’Inondation Dans La Basse Vallée De L’Ouémé : Causes Et Conséquences

RésuméLa gouvernance des inondations intègre une dimension « adaptative » face aux changements continus, caractéristiques des sociétés contemporaines. L’objectif de cette étude est d’analyser l’implication des pouvoirs publics, des populations et partenaires sociaux dans la gouvernance des inondations dans la basse vallée de l’Ouémé. Les données utilisées à cet effet concernent les relevés hydroclimatiques, celles liées aux incidences socio-économiques des inondations et des statistiques épidémiologiques. La gouvernance adaptative des inondations dans la basse vallée de l’Ouémé implique une multitude d’acteurs à différents niveaux de gestion coordonnée.Mots clés : Gouvernance adaptative, co-gestion, inondation, changement climatique, basse vallée de l’Ouémé AbtsractThe governance of floods integrates an « adaptive » dimension in the face of continuous changes, characteristic of contemporary societies. The objective of this study is to analyze the involvement of public authorities, populations and social partners in food governance in the Ouémé valley. The data used for this purpose concern hydroclimatic surveys, those related to the socio-economic impacts of floods and epidemiological statistics. The adaptative governance of flood in the lower Ouémé valley involves a multitude of actors of coordinated management.Keys words: Adaptative governance, co-management, flood, climate change, lower valley of Ouem

Screening of medicinal plants from Reunion Island for antimalarial and cytotoxic activity

International audienceAim of the study Nine plants from Reunion Island, selected using ethnopharmacology and chemotaxonomy, were investigated for their potential antimalarial value. Materials and methods Thirty-eight extracts were prepared by maceration using CH2Cl2 and MeOH, and were tested for in vitro activity against the 3D7 and W2 strain of Plasmodium falciparum. The most active extracts were then tested for in vitro cytotoxicity on human WI-38 fibroblasts to determine the selectivity index. Those extracts were also investigated in vivo against Plasmodium berghei infected mice. Results Most active of the extracts tested were the dichloromethane leaves extracts of Nuxia verticillata Lam. (Buddlejaceae), Psiadia arguta Voigt. (Asteraceae), Lantana camara L. (Verbenaceae), the methanol extracts from Aphloia theiformis (Vahl) Benn. (Aphloiaceae) bark, and Terminalia bentzoe L. (Combretaceae) leaves displaying in vitro IC50 values ranging from 5.7 to 14.1 μg/ml. Extracts from Psiadia, Aphloia at 200 mg/(kg day) and Teminalia at 50 mg/(kg day) also exhibited significant (p \textless 0.0005) parasite inhibition in mice: 75.5%, 65.6% and 83.5%, respectively. Conclusion Two plants showed interesting antimalarial activity with good selectivity: Aphloia theiformis and Terminalia bentzoe. Nuxia verticillata still needs to be tested in vivo, with a new batch of plant material