Jelena Bogdanovic

Changes in activities of antioxidant enzymes during Chenopodium murale seed germination

The activities and isoenzyme pattern of catalase (CAT), superoxide dismutase (SOD) and peroxidase (POD) have been studied during germination of Chenopodium murale seeds. CAT and SOD activities were similar in dry seeds and during first 2 d of imbibition. CAT activity increased during radicle protrusion and early seedling development. The maximum SOD activity was found at final stages of germination and early seedling development. POD activity was not detected until the 6th day of germination, indicating POD involvement not until early seedling development. Gibberellic acid (GA3, 160 µM) delayed and synchronized C. murale germination.

Effect of photoperiod during growth of Chenopodium rubrum mother plants on properties of offspring

Using in vitro culture, we determined the effect of photoperiod during growth of Chenopodium rubrum mother plants on vegetative and reproductive development of offspring. Photoperiod during flowering induction of mother plants (the first 6 d after the germination) has the key influence on seed germination and offspring growth, while offspring flowering and seed maturation is determined by photoperiod their mothers experienced during, and shortly after, flowering induction. The mechanism can be through changes in seed protein pattern which we found dependent on photoperiod experienced by mother plants.

Phenolics, lignin content and peroxidase activity in Picea omorika lines

We analyzed low molecular mass phenolics, lignin content and both soluble and cell wall bound peroxidase activity in the needles of three Picea omorika (Pancic) Purkyne lines grown in the generative seed orchard. The highest values of the total phenol content as well as of catechine, caffeic acid, coniferyl alcohol, isoferulic acid and lignin concentration were detected in B5 line (“semidichotomy” line). The soluble guaiacol peroxidase activity was the highest in A3 line (line “borealis”). The highest activity of cell wall bound peroxidases was measured in B5 line, and it was in correlation with lignin content.

Levels of plant cell wall structural organization revealed by atomic force microscopy.

We used an atomic force microscope to image cell wall isolated from needles of Serbian spruce tree and that synthesized from cell wall components. We also observed the structure of lignin model polymer (DHP), as a best substitute for the natural lignin. A tendency of aggregate formation was observed in all samples. Cell wall was revealed as a laminated fibrous structure. General organization is similar in both isolated and synthesized cell wall samples, with dominating globular motifs arranged regularly as rods and forming cavities. The synthesized cell wall has a more regular structural organization than isolated cell wall. The dimensions of individual globular aggregates and pores differed between the two samples. DHP showed a similar, regular organization, with globular aggregates and holes. Globules and pores are smaller in size than the corresponding structures in both the isolated and synthesized cell walls. Such modular organization of cell walls may have a physiological role in response to the external mechanical stress caused to plant cells.

Characterization of Enzymatically Synthesized Diferulate

Abstract: Horseradish peroxidase was used to synthesize diferulates by a procedure in which ethyl ferulate was used as substrate. Four different forms were obtained, of which two dominant were the 5‐5′ and 8‐5′ diferulate. Fluorescence emission spectra of the diferulates (excited at 284 nm) indicate that they contain two chromophores, as opposed to the substrate molecule. Fluorescence excitation spectra with emission at 417 nm further demonstrate the difference between the synthesized diferulates and starting substrates.