No abstract

In this study, poplar tissue culture (hybrid black poplar, M1 genotype) was subjected to water stress influenced by polyethyleneglycol 6000 (100 and 200 mOsm PEG 6000). The aim of the research was to investigate the biochemical response of poplar tissue culture on water deficit regime. Antioxidant status was analyzed including antioxidant enzymes, superoxide-dismutase (SOD), catalase (CAT), guiacol-peroxidase (GPx), glutathione-peroxidase (GSH-Px), glutathione-reductase, reduced glutathione, total phenol content, Ferric reducing antioxidant power and DPPH radical antioxidant power. Polyphenol oxidase and phenylalanine-ammonium-lyase were determined as enzymatic markers of polyphenol metabolism. Among oxidative stress parameters lipid peroxidation, carbonyl-proteins, hydrogen-peroxide, reactive oxygen species, nitric-oxide and peroxynitrite were determined. Proline, proline-dehydrogenase and glycinebetaine were measured also as parameters of water stress. Cell viability is finally determined as a biological indicator of osmotic stress. It was found that water stress induced reactive oxygen and nitrogen species and lipid peroxidation in leaves of hybrid black poplar and reduced cell viability. Antioxidant enzymes including SOD, GPx, CAT and GSH-Px were induced but total phenol content and antioxidant capacity were reduced by PEG 6000 mediated osmotic stress. The highest biochemical response and adaptive reaction was the increase of proline and GB especially by 200 mOsm PEG. While long term molecular analysis will be necessary to fully address the poplar potentials for water stress adaptation, our results on hybrid black poplar suggest that glycine-betaine, proline and PDH enzyme might be the most important markers of poplar on water stress and that future efforts should be focused on these markers and strategies to enhance their concentration in poplar.

This work is aimed to compare antioxidant and scavenger properties of conventionally and organically produced speltgrass. Moreover, the antioxidant status of spelt was compared with wheatgrass. Three spelt varieties were analyzed:Nirvana, Ebners–Rotkorn variety and Eco-10. Antioxidant enzymes, superoxide-dismutase and guiacol-peroxidase, were determined as well as ferric reducing antioxidant power and DPPH-antiradical power. Total soluble proteins and total phenols were determined and also lipid peroxidation as a parameter of oxidative stress. The organically produced spelt was exposed to the higher levels of oxidative stress than conventionally produced spelt, and also DPPH antiradical power was induced by conventional production, which is also demonstrated using the relative antioxidant capacity index. The best antioxidant properties, better than wheat, showed organically produced spelt genotype Ebners–Rotkorn which is determined by the highest phenol content, superoxide-dismutase activity, DPPH antiradical power and ferric reduced antioxidant power and consequently with the lowest lipid peroxidation intensity.