Activity of Haliscosamine against Fusarium oxysporum f.sp. melonis: in vitro and in vivo analysis.

Marine sponges are a potential source of new molecules with diverse biological activities. We have previously isolated a sphingosine derivative, (9Z)-2-amino-docos-9-ene-1,3,13,14-tetraol (Haliscosamine) from the Moroccan sea sponge Haliclona viscosa. The aim of this study was to test Haliscosamine in vitro and in vivo for its antifungal activity against Fusarium oxysporum f.sp. melonis causing fusarium wilt of melon. Overall, in vitro test showed that haliscosamine has a similar effect as DESOGERME SP VEGETAUX®. In addition, in vivo showed a significant effect against Fusarium oxysporum f.sp. melonis. Taking to gather, our results suggest that haliscosamine constitutes a potential candidate against Fusarium oxysporum f.sp. melonis and the possibility to use in phytopathology.

Direct identification and characterization of phenolic compounds from crude extracts of buds and internodes of grapevine (Vitis vinifera cv Merlot).

The crude methanol extracts of latent buds and internodes Vitis vinifera L. cv. Merlot were used for the determination of phenolic compounds by a combination of reverse phase HPLC with diode array detection (HPLC-DAD) and mass spectrometry (LC-MS). This method allowed the identification of 9 phenolic compounds without purification or fractionation. These 9 compounds were divided into three groups: procyanidins, flavonols and stilbenes. Detection by HPLC-DAD at different wave lengths of 280 nm to 320 nm, allowed the estimation of concentrations of those compounds. This method permitted, for the first time, both characterization and quantification of polyphenolic compounds in buds of grapevine. Comparison with the results obtained in internodes showed that quercetin, resveratrol tetramer and ε-viniferin had similar levels in buds and internodes while six other compounds identified had higher levels in buds.

Enhanced salt-induced antioxidative responses involve a contribution of polyamine biosynthesis in grapevine plants.

The possible involvement of polyamines in the salt stress adaptation was investigated in grapevine (Vitis vinifera L.) plantlets focusing on photosynthesis and oxidative metabolism. Salt stress resulted in the deterioration of plant growth and photosynthesis, and treatment of plantlets with methylglyoxal-bis(guanylhydrazone) (MGBG), a S-adenosylmethionine decarboxylase (SAMDC) inhibitor, enhanced the salt stress effect. A decrease in PSII quantum yield (Fv/Fm), effective PSII quantum yield (Y(II)) and coefficient of photochemical quenching (qP) as well as increases in non-photochemical quenching (NPQ) and its coefficient (qN) was observed by these treatments. Salt and/or MGBG treatments also triggered an increase in lipid peroxidation and reactive oxygen species (ROS) accumulation as well as an increase of superoxide dismutase (SOD) and peroxidase (POX) activities, but not ascorbate peroxidase (APX) activity. Salt stress also resulted in an accumulation of oxidized ascorbate (DHA) and a decrease in reduced glutathione. MGBG alone or in combination with salt stress increased monodehydroascorbate reductase (MDHAR), SOD and POX activities and surprisingly no accumulation of DHA was noticed following treatment with MGBG. These salt-induced responses correlated with the maintaining of high level of free and conjugated spermidine and spermine, whereas a reduction of agmatine and putrescine levels was observed, which seemed to be amplified by the MGBG treatment. These results suggest that maintaining polyamine biosynthesis through the enhanced SAMDC activity in grapevine leaf tissues under salt stress conditions could contribute to the enhanced ROS scavenging activity and a protection of photosynthetic apparatus from oxidative damages.