BIOLOGIA PLANTARUM 56 (2): 357-361, 2012 357 BRIEF COMMUNICATION Changes in antioxidative enzymes activities during Tacitus bellus direct shoot organogenesis A. MITROVIĆ 1 *, D. JANOŠEVIĆ 2 , S. BUDIMIR 3 and J. BOGDANOVIĆ PRISTOV 1 Institute for Multidisciplinary Research 1 and Institute for Biological Research “Siniša Stanković” 3 , University of Belgrade, Bulevar despota Stefana 142, Belgrade, 11000, Serbia Institute of Botany and Botanical Garden „Jevremovac“,University of Belgrade, Takovska 43, Belgrade, 11000, Serbia 2 Abstract Changes in antioxidative enzymes activities during Tacitus bellus direct shoot organogenesis from leaf explants were examined. During the early stages of shoot organogenesis there was a decrease in superoxide dismutase (SOD) and an increase in catalase (CAT) activity, and later during organogenesis there was an increase in peroxidase (POD) and polyphenol oxidase (PPO) activity. Two highly regulated turning points may be distinguished regarding activities and isoforms of antioxidative enzymes: the initiation of shoot organogenesis and the shoot bud formation. Our data suggest the role of specific CAT, POD, SOD and PPO isoforms in separate processes during T. bellus direct shoot organogenesis. Additional key words: catalase, peroxidase, polyphenol oxidase, superoxide dismutase. ⎯⎯⎯⎯ Organogenesis is a complex process accompanied with expression of various genes and protein synthesis. Organ initiation and development in plant explants involves promotion of meristematic activity, its maintenance in some regions and its concomitant suppression in regions of maturation (Kay and Basile 1987). Reactive oxygen species (ROS) and their scavenging enzymes participate in protection against pathogens or abiotic stress (Hendry and Crawford 1994), in regulation of plant growth and developmental processes (Mitrović and Bogdanović 2008), and in processes linked with development, differentiation and growth of plant cells during morphogenesis in vitro. It was shown that H 2 O 2 content and activities of superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD) are correlated with bud primordium formation in strawberry callus (Tian et al. 2003). Involvement of CAT and POD in direct adventitious shoot formation was detected in eastern white pine (Tang and Newton 2005), in Gladiolus hybridus (Gupta and Datta 2003/4). Kay and Basile (1987) examined the role of specific isoperoxidases in different developmental processes during organogenesis in tobacco. The role of polyphenol oxidase (PPO) in defence against pathogens, in cell division and root primordia development was suggested, but its physiological function is not clear (Mayer 2006). In vitro culture is a useful model system for the investigations of morphological, biochemical and molecular processes linked with early development of plants. In this study we used Tacitus bellus as a model plant. Earlier we reported T. bellus in vitro micropropagation and ex vitro acclimation (Mitrović et al. 2005). The aim of this study was to examine the correlation between activities of antioxidative enzymes and different phases of T. bellus ⎯⎯⎯⎯ Received 27 April 2010, accepted 22 October 2010. Abbreviations: BAP - benzylaminopurine; CAT - catalase; EDTA - ethylenediaminetetraacetic acid; NAA - naphtaleneacetic acid; POD - peroxidase; PPO - polyphenol oxidase; PVP - polyvinylpyrrolidone; SOD - superoxide dismutase; SDS - sodium dodecyl sulfate; TRIS - tris(hydroxymethyl)aminomethane. Acknowledgements: This work was supported by a grant (No. 173017 and 173015) from the Ministry of Education and Science of the Republic of Serbia. * Corresponding author: fax: (+381) 113055289, e-mail: mita@imsi.rs