When attacked, plants activate defense mechanisms including volatile emission. Besides havinga pest repellent effect, volatiles can induce defense response in surrounding unharmed plants.French marigold (Tagetes patula L.) essential oil (EO) was isolated from the above-ground partsof plants collected from nature by hydrodistillation using Clevenger apparatus. GC/MS analysisrevealed the presence of 42 compounds, of which 97% (32 compounds) have been identified.The monoterpene fraction was dominant (76.9%) with terpinolene (32.4%) and limonene (14.7%)as the most abundant compounds. In order to investigate the potential of marigold EO to inducethe defense of potato, we analyzed 3 genes related to the induced resistance (IR): pathogenesisrelated PR-2 and PR-5 genes, and proteinase inhibitor Pin2. The potato plants were exposed to EOvolatiles during 4, 8 and 12 h. Two leaves of EO-treated or untreated control plants were collected,and plants were then additionally injured by mechanically wounding leaves across the leaf surface.After 24 h of wounding, another two leaves from each plant were collected and expressionof the IR related genes was analyzed by qPCR method. EO induced altered expression of PR genes,while Pin2 wasn’t affected by the treatment. Mechanical wounding increased the expression ofall genes after 4 and 8 h of EO treatment, with up to 4-fold change in PR-2. However, in plantsexposed to EO for 12 h before wounding, the level of transcription in PR-2 and Pin2 was similar tothat detected in untreated controls. These findings support the efforts for environmentally-safepest control in crops by using natural compounds.Uzelac B, editor. Book of abstracts. 3rd International Conference on Plant Biology (22nd SPPS Meeting); 2018 Jun 9-12; Belgrade, Serbia. Belgrade: Serbian Plant Physiology Society; Institute for Biological Research "Siniša Stanković"; Faculty of Biology; 2018. p. 58
