Methyl Jasmonate Elicited Helichrysum stoechas (L.) Moench Cell Suspensions, A Promising Source of Extracts with Allelopathic Activity?

International audienceHelichrysum stoechas (L.) Moench cell suspensions were analyzed by LC-ESI-QTOF, which highlighted the predominance of 3,5-O-dicaffeoylquinic acid (3,5-diCQA). Elicitation of H. stoechas cells with methyl jasmonate (200 mM) led to a massive rise in 3,5-diCQA, up to 5-fold-increase compared with control, reaching the concentration of 10.2 mg. g-1dry weight after 14 days of culture. Previous data showed that diCQA isomers are potent allelopathic compounds, thus the methanolic extracts of control and MeJa-elicited H. stoechas cells were tested for their phytotoxicity. With this in mind, activity on the seed germination and seedling growth of the model plant Lepidium sativum were tested. Phytotoxicity of both extracts occurred in a dose-dependent manner, with a greater activity of elicited cells extract. Indeed, in the concentration range from 0.31 to 0.83 mg. mL-1, the latter showed a significantly higher inhibition rate of L. sativum seedlings root growth, when compared to control cells extract. The data presented may contribute to explore new strategies towards the conception of bioherbicides from plant origin. To our knowledge, this study is the first report of the use of elicited plant cells grown in vitro as a raw material for the production of allelopathic metabolites

Cloning of Arabidopsis thaliana glutathione synthetase (GSH2) by functional complementation of a yeast gsh2 mutant.

Glutathione (L-gamma-glutamyl-L-cysteinylglycine, GSH) plays an important role in the protection of plants against various types of stress caused by reactive oxygen species, gazeous pollutants, heavy metals and xenobiotics. A cDNA fragment containing the entire coding unit for glutathione synthetase (GSH2) of Arabidopsis thaliana was cloned by complementation of the methylglyoxal sensitivity of a gsh2 mutant of the yeast Saccharomyces cerevisiae. The cDNA encodes a protein of 478 amino acids (deduced Mr: 53783), bearing clear sequence similarities to GSH2 products from frog embryos (Xenopus laevis), rat kidney (Rattus norvegicus) and from the fission yeast (Schizosaccharomyces pombe). A highly conserved glycine-rich domain close to the carboxy-terminus was found in the GSH2 product and appears to be typical for eukaryotic glutathione synthetases. The Mr is similar to those of soluble animal enzymes, suggesting that the Arabidopsis gene also codes for a cytosolic protein. Genomic DNA-blot analysis indicates the presence of a single GSH2 gene. The yeast gsh2 mutant becomes resistant to methylglyoxal and cadmium after transformation with the plasmid bearing the Arabidopsis GSH2 cDNA. Moreover, this increased resistance is correlated to the restoration of GSH content from below detectability in mutants to about 50% of the wild-type levels in transformed cells.comparative studyjournal article1996 Mar 01importe

Isotope ratios of H, C, and O in CO2 and H2O of the Martian atmosphere

Stable isotope ratios of H, C, and O are powerful indicators of a wide variety of planetary geophysical processes, and for Mars they reveal the record of loss of its atmosphere and subsequent interactions with its surface such as carbonate formation. We report in situ measurements of the isotopic ratios of D/H and O-18/O-16 in water and C-13/C-12, O-18/O-16, O-17/O-16, and (CO)-C-13-O-18/(CO)-C-12-O-16 in carbon dioxide, made in the martian atmosphere at Gale Crater from the Curiosity rover using the Sample Analysis at Mars (SAM)'s tunable laser spectrometer (TLS). Comparison between our measurements in the modern atmosphere and those of martian meteorites such as ALH 84001 implies that the martian reservoirs of CO2 and H2O were largely established similar to 4 billion years ago, but that atmospheric loss or surface interaction may be still ongoing