The accumulation of conjugated and free polyamines in plants is very important for their protection against oxidative stress induced by abiotic factors. In the present study, the species halophytic plant Mesembryanthemum crystallinum L. was used as a model system in which the process of Crassulacean Acid Metabolism induction is linked with oxidative stress, especially under salinity conditions. A comparative analysis of the content of free polyamines, perchloric (PCA)-soluble and PCA-insoluble conjugated polyamines in mature leaves and roots was carried out with plants exposed to salinity. It was found that adult leaves and roots under normal conditions or salinity (400 mM NaCl) contained all types of free polyamines (putrescine, spermidine, spermine, and cadaverine). In leaves only PCA-insoluble conjugates were found, which showed a tendency to grow with increased duration of salt action (1.5-48 h). In contrast to leaves, in roots all forms of polyamine conjugates (PCAsoluble and -insoluble) were detected. However, the formation of all conjugates, especially PCAsoluble forms in roots, was sharply inhibited by salt shock (400 mM NaCl, 1.5 h) or exogenous cadaverine (1 mM) treatment. PCA-soluble conjugates of cadaverine in roots were found only when the treatment was carried out in combination with aminoguanidine (1 mM), as a result of diamine oxidase inhibition and consequently a decreasing of H 2 O 2 production in plant cells. The activation of diamine oxidase and guaiacol peroxidase by NaCl or exogenous cadaverine was observed in leaves and roots. Thus, the activation of oxidative degradation of polyamines combined with H 2 O 2 -peroxidase reaction in cells are involved in the regulation of free and conjugated polyamines titers under salinity.
Comparative studies of the adaptation of green-and purple-leaved Ocimum basilicum varieties, which differ in carotenoid and anthocyanin contents, to high-intensity light have been carried out. The plants were grown for 21 d under white lightemitting diode providing different light intensities [300, 550, and 1,350 µmol(photon) m-2 s-1 ]. During the experiment, fresh mass and relative water content, photosynthetic pigment and anthocyanin content, amount of total free phenolic compounds, and the contents of thiobarbituric acid reactive substances and H2O2 were analysed. The fluorescent parameters, which characterized the PSII activity in the leaves (Fv/Fm, Y(II)), as well as the efficiency of dissipation of absorbed energy into heat (Y(NPQ),Y(NO)) and the fraction of the PSII open centres (qL), were determined. The obtained results are consistent with the concept of the important role of not only anthocyanin but also carotenoids in plant adaptation to high-intensity light.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.