Genetics and Plant PhysioloGy – 2016, V olume 6(3–4), PP. 167–175 ©2016 Published by the Institute of Plant Physiology and Genetics – Bulgarian Academy of Sciences Available online at http://www.ifrg-bg.com ReseaRch aRticle * Corresponding author: gchaneva@abv.bg Received: 13 October 2016 Accepted: 04 November 2016 CHANGES OF SOME OXIDATIVE STRESS MARKERS IN BEECH LEAVES AFTER ORCHESTES FAGI INFESTATION Lamlom S. 1 , S. Georgieva 2 , P. Dimitrova-Mateva 3 , S. Anev 4 , N. Tzvetkova 4 , G. Chaneva 5* 1 Faculty of Natural Resources and Environmental Sciences, University of Omar Al- Mukhtar, Al Bayda, Libya 2 B.Sc. student, University of Forestry, Sofa, Bulgaria 3 South-West State Enterprise - Blagoevgrad, Ministry of Agriculture and Food, Bulgaria 4 Department of Dendrology, University of Forestry, Sofa, Bulgaria 5 Department of Plant Physiology, Sofa University “St. Kl. Ohridski”, Sofa, Bulgaria Summary: The present work focused on the infuence of leaf-mining weevil (Orchestes fagi L.) on the leaves of common beech (Fagus sylvatica L.). The study investigated the changes of the oxidative stress markers malone dialdehyde (MDA), total peroxides and free proline in beech trees located at two different altitudes (680 m asl and 1400 m asl) at the Petrohan Training and Experimental Forest Range, Western Balkan Mountains. Levels of infestation as well as the studied parameters were highly dependent on the location. The conditions at low altitude were favorable for the rapid development of O. fagi which resulted in signifcant changes of leaf growth and physiology. The peak of the invasion was reached in May – June, 2015. Malone dialdehyde was the most reliable oxidative marker among the examined parameters. The heavily damaged leaves at 680 m asl contained higher amount of MDA – 24% - 35% more than that in the leaves at the higher altitude. Statistically signifcant correlation between content of MDA and degree of infestation was established. However, the increased level of lipid peroxidation was not accompanied by the corresponding enhancement of total peroxides. The damage caused by O. fagi invasion was also manifested by the increase of free proline content, especially in the leaves at 680 m asl. In general, the herbivory resulted in serious biochemical changes occurring in the leaves, indicating a shift in the oxidative status of the beech trees. Keywords: Fagus sylvatica; Orchestes fagi; MDA; total peroxides; proline. Citation: Lamlom S., S. Georgieva, P. Dimitrova-Mateva, S. Anev, N. Tzvetkova, G. Chaneva, 2016. Changes of some oxidative stress markers in beech leaves after Orchestes fagi infestation. Genetics and Plant Physiology, 6(3–4): 167–175.