STSM2 Report Marija Vidovic2

UV-B irradiation and light excess

Marija Vidovic visited Dr. Jana Barbro Winkler in Germany (21 days in April/May 2012).

UV-B irradiation and light excess: synergistic or individual action on mobilization of secondary metabolites in variegated leaves. Influence on photosynthesis.

This research is continuation of collaboration with Dr. Jana Barbro Winkler and Dr. Andreas Albert. Previously, we have shown that UV-B irradiation combined with excess of light was not detrimental for plant photosynthetic system. Having obtained results in mind, our idea was to expose the same plants species (Pelargonium zonale variegata and Plectranthus coleoides) to the same conditions regarding temperature, humidity and UV-B irradiance but combined with low PAR intensities. In brief, the results of this experiment showed that UV-B exposure induce statistically relevant changes of quantum yield of photosynthesis, while no changes were observed for main photosynthesis parameters. It was unambiguously showed that photosystem II in each plant group was not stressed or damaged by UV-B exposure. Regarding CO2 assimilation rate, stomatal conductance and transpiration rate for P. zonale plants statistical analysis revealed more significant changes during the first half of treatment. The DAB staining procedure for H2O2 visualization showed that in P. zonale plants no H2O2 generation was detected neither in control neither in UV-B exposed plants, while in the P. coleoides the higher amount of H2O2 was found in UV-B treated plants.

Taken all together, I am very satisfied with everything we have achieved during this short period. This STSM enhances the collaboration between the two work groups. Now we have to integrate all obtained results and try to reveal the UV-B response in these metabolically different leaf tissues, with respect to different plant species.