No abstract

Cirak C., Radusiene J., Aksoy H.M., Mackinaite R., Stanius Z., Camas N., Odabas M.S. (2014): Differential phenolic accumulation in two Hypericum species in response to inoculation with Diploceras hypericinum and Pseudomonas putida. Plant Protect. Sci., 50: 119-128.The genus Hypericum L. (St. John's-wort, Hypericaceae) has received scientific interest in recent years, because it is a source of a variety of bioactive compounds including the phenolics. We determine whether the typical phenolic constituents of Hypericum plants, namely chlorogenic acid, rutin, hyperoside, isoquercetine, quercitrine, and quercetine, may be implicated as part of an inducible plant defence response in two St. John's-wort species, Hypericum perforatum L. and Hypericum triquetrifolium Turra. To achieve this objective, greenhouse-grown plantlets were inoculated with the fungal pathogen Diploceras hypericinum and the plant growth promoting bacterium Pseudonomas putida. Phenolic compounds levels of the Hypericum plantlets increased significantly in response to inoculation with both organisms. So far, little effort has been dedicated to investigate whether phenolic compounds are inducible by pathogen/herbivore attack or if they could play a role in plant defence. Results from the study indicate that the phenolic compounds investigated could be involved in the plant defence system and implicated as part of an inducible plant defence response in both St. John's Wort species.Keywords: fungal pathogen; Hypericum perforatum; Hypericum triquetrifolium; phenolic compounds; plant defence; bacterial infectionHypericum perforatum L. is a well-known traditional medicinal plant that has been used for centuries for the treatment of several diseases, such as skin lesions, eczema, burns and microbial, inflammatory, and psychological disorders (Sanchez-Mateo et al. 2002). The crude extract of H. perforatum is now widely used in Europe as a drug for the treatment of depression. Proven photodynamic, antiviral, antiretroviral, and antitumor effects of Hypericum extracts also suggest using this plant in in the case of Acquired Immune Deficiency Syndrome (AIDS) and cancer treatments (Guedes & Eriksson 2005). Hypericum triquetrifolium Turra is another widespread species of Hypericum genus. It has traditionally been used in the treatment of burns and gastrointestinal disease in Turkish folk medicine (Baytop 1999). Results from recent studies reporting anti-inflammatory (Ozturk et al. 2002), antibacterial (Pistelli et al. 2005, antifungal (Fraternalea et al. 2006), antioxidant, and cytotoxic (Conforti et al. 2007) activities of H. triquetrifolium sign out the great potential of this species as a promising medicinal plant. 120Vol. 50, 2014, No. 3: 119-128 Plant Protect. Sci.Chemistry of Hypericum genus has been extensively investigated and it has been shown that methanolic extract from the aerial parts of Hypericum plants typically contains hypericins, hyperforins, and several phenolic compounds, altogether good candidates for the activity of the drug (Pat...

No abstract

Barley developmental mutants tweaky spike (tw) with disturbed auxin pathways possess a unique feature of an increased level of mouldy germinating grains (MGG), which serves as a convenient model to investigate the effects of plant immunity-related substances. The effects of the auxin 2,4-dichlorophenoxyacetic acid (2,4-D), auxin inhibitors, salicylic acid (SA), and trans-cinnamic acid (TCA) were studied using the tw-WT system in surface-sterilized and unsterilized germinating grains under high rates of natural infection. Significant differences among the allelic tw mutants were revealed at the natural MGG level and in response to 2,4-D, SA, and TCA. The most effective means against MGG were sterilization and TCA. 2,4-D inhibited root growth in tw and tw2 mutants, occurring only in unsterilized and not sterilized germinating grains, while the opposite was observed for TCA and SA. The tw mutations influenced variations in the seed-borne fungal spectra, decreasing the frequency of Bipolaris sorokiniana and increasing Fusarium spp. Hypochlorite-based surface sterilization methods should be used with caution in studies where the action of exogenous 2,4-D will be analysed in germinating grains. Auxin pathway disturbances specific for pleiotropic tw mutants are generally restricted to organogenesis but not to germination events.

No abstract