10th Symposium on the Flora of Southeastern Serbia and ...

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10 th <strong>Symposium</strong> on the Flora of Southeastern Serbia and Neighbouring regions,Vlasina 17 to 20 June 2010since cold-related oxidative damage leads to Mn2+ release from photosystem II.Seasonal changes were found to affect enzymatic activities and isoenzyme profiles.Several isoforms of peroxidase, catechol oxidase and superoxide dismutase, as wellas two catalase isoenzymes were detected. The number of peroxidase isoenzymeswas greatest during the vegetative season. The results obtained show that there aretwo gro ups of antioxidant enzymes in P. omorika needles that change levels ofactivities in the spring/summer and autumn/winter seasons. Catalase and catecholoxidase peaked in summer and spring, respectively. During the autumn/winterseason, however, both total SOD and Mn-SOD showed maximum activity. It wasobserved that prooxidative conditions developed in the autumn, at the beginning ofcold season, which corresponded to significant increase of MnSOD activity. Thissuggests a complementary action of these enzymes in reaction to external changes.Chenopodium murale L., a long-day plant, as a model plantfor physiological and biochemical researchŽivanović, B. 1 , Mitrović, A. 1 , Bogdanović Pristov, J. 1 , Radotić Hadži-Manić, K. 1 , Ćulafić, Lj. 21 Institute for multidisciplinary research, University of Belgrade, Belgrade,Serbia2 Institute of Botany and Botanical Garden "Jevremovac", Faculty of Biology,University of Belgrade, Belgrade, SerbiaChenopodium murale L. plant belongs to the family Chenopodiaceae, genusChenopodium which is widely distributed in Serbia as long-day weedy annual plant.Chenopidium murale is also a facultative long-day plant, and an early floweringspecies. Experiments were performed on in vitro cultured Chenopodium murale L.plants grown on optimal culture medium and exposed to adequate photoperiodicregime. The effects of glucose and GA 3 on flowering under inductive photoperiodicconditions were tested. Glucose and GA 3 stimulated the flowering of C.murale. Weshowed that exposure of aged vegetative plants to continuous darkness leaded toflowering, as transferring to darkness cancelled photoperiodic control in C.muraleand flowering occured under autonomous mechanism. The seeds were produced invitro within 18 weeks and the antioxidative enzymes were analysed during seedgermination. The results presented indicate a sequential expression of theantioxidative enzymes and their importance in seed germination. Changes in catalase(CAT), superoxide dismutase (SOD) and peroxidase (POD) activities could berelated to different phases of seed germination. Decrease in SOD activity, increasein CAT and appearance of POD activity coincide with early seedling development inC. murale. Gibberellic acid (GA 3 ) delayed and synchronized C.murale germination.80
10 th <strong>Symposium</strong> on the Flora of Southeastern Serbia and Neighbouring regions,Vlasina 17 to 20 June 2010Thus we suggest to use C.murale as a suitable model plant for investigation ofphysiological and biochemical mechanisms of growth and developmental processes.Dynamics of sexually dimorphic traits in Mercurialisperennis L. (Euphorbiaceae) from Suva planinaJovanović, V., Cvetković, D.Biološki fakultet, Univerzitet u Beogradu, Srbijadragana@bio.bg.ac.rsSexual dimorphism (SD) is a common phenomenon that has attracted muchresearch interest, but it has been far less studied in plants. In addition, although SDaffects many aspects of phenotype, previous studies on plant species tended to leavesome issues, like overall plant size or temporal patterns of variation in SD, out offocus. The aim of this study was to examine interannual variation in sexuallydimorphic traits in male and female individuals of Mercurialis perennis L.(Euphorbiaceae), a dioecious anemophilous species with wide geographic andaltitudinal distribution in Europe. During a 3-year period (2007–2009), weinvestigated a population of M. perennis from Suva planina (at the altitude of 1100m asl) and analyzed the following traits: plant size (above-ground height), number offlowers per plant and the extent of reproductive allocation (RA). We found moderatevalues of male-biased size dimorphism and a decreasing trend in absolute values ofsexual dimorphic index (SDI), from 0,087 in 2007 to 0,030 in 2009; intersexual sizedifference was significant only in 2007 sample. Both sexes flowered at smaller sizesin 2009 compared to previous years, but no trend was observed for the number offlowers per plant. Female plants invested more in reproduction; difference in RAwas significant not only between sexes, but between years as well – the estimatedRA values were significantly greater in 2009 than in 2008 in both sexes. We discussthe obtained results in the context of current hypotheses concerning size dimorphismand differences in resource investment.81
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