S25 - Session O3 - Regulation of secondary metabolites of basil (Ocimum basilicum L.) by the application of elicitors in vivo

Authors: Wafae Kandoudi *, Éva Zámboriné Németh

Sweet basil ( Ocimum basilicum L .) is one of the most popular species of the Lamiaceae family. Commonly used as a flavoring agent in food as a fresh or dried herb, as well as in perfumery and pharmaceutical preparations (Hussain et al. 2008). The leaves are rich in volatile components, among which linalool, camphor, and methyl-chavicol are present in the highest ratios, depending on the chemotype. It has been used extensively for its antioxidant, antimicrobial, stomachic, and larvicidal properties, as well as its health-promoting effects.(Kwee and Niemeyer 2011; Pushpangadan and George 2012). Because of the low occurrence in the plants and the extensive industrial demand, several strategies were studied to increase the secondary metabolites (SMs) of medicinal and aromatic plants, including elicitation (Radman et al.,2003). The application of elicitors on plants triggers defense reactions, which might lead to an increase in the production of SMs including volatile components and phenolic content (Klessig et al.,2018). The aim of this study is to investigate the effect of exogenous application of two of the most important phytohormones as elicitors, methyl jasmonate (MeJa) and salicylic acid (SA) on the essential oil (EO) content, chemical composition, total phenolic content, and antioxidant activity of basil ( Ocimum basilicum ). The first experiment was carried out in a greenhouse at Buda Campus of the Hungarian University of Agriculture and Life Sciences in Budapest, Hungary. A total of 10 plants at the same developmental stage were chosen for each treatment and each dosage. While the second experiment was established in an open field experiment at the experimental station of MATE in Budapest. Two dosages (0.1mM and 2mM) of each elicitor were applied twice with an interval of one week. After a week from the second treatment, aerial parts of the plants were harvested and air-dried in a shady place with ambient temperature. The experiments were arranged in a completely randomized block design with a plot size of 10 m2 in three replications for each treatment. The essential oil of the dried materials from each sample was hydro-distilled in a Clevenger type apparatus and investigated by GC/MS. The quantification of total phenolic content was determined by the modified method of Singleton and Rossi (1965). The antioxidant capacity was determined by the application of the ferric reducing antioxidant power (FRAP) assay developed by Benzie and Strain (1996). Our results suggest Elicitation in-vivo may be used as a tool to influence the accumulation of SM. However, the elicitation does not depend only on the type of elicitor, but also on the concentration used and the type of the accumulated compound. Acknowledgment This research was supported by the Ministry for Innovation and Technology, Institutional Excellence Subprogram (TKP2020-IKA-12) and by EU-Erasmus+ EOHUB project (600873-EPP-1-2018-1ES-EPPKA2-KA). REFERENCES Benzie, I. F. F.; Strain, J. J. 1996. The Ferric Reducing Ability of Plasma (FRAP) as a Measure of "'Antioxidant Power'": The FRAP Assay. Anal. Biochem., 239, 70n76. https://doi.org/10.1002/(SICI)1097-0010(20000515)80:7. Hussain, Abdullah Ijaz, Farooq Anwar, Syed Tufail Hussain Sherazi, and Roman Przybylski. 2008. "Chemical Composition, Antioxidant and Antimicrobial Activities of Basil ( Ocimum basilicum ) Essential Oils Depends on Seasonal Variations." Food Chemistry 108(3):986n95. doi: 10.1016/j.foodchem.2007.12.010. Kwee, Eileen M., and Emily D. Niemeyer. 2011. "Variations in Phenolic Composition and Antioxidant Properties among 15 Basil ( Ocimum Basilicum L.) Cultivars." Food Chemistry 128(4):1044n50. doi: 10.1016/j.foodchem.2011.04.011. Klessig, D. F., Choi, H. W., & Dempsey, D. A. 2018. Systemic acquired resistance and salicylic acid: Past, present, and future. Molecular Plant-Microbe Interactions , 31 (9), 871n888. https://doi.org/10.1094/MPMI-03-18-0067-CR Pushpangadan, P., and V. George. 2012. "Basil." Pp. 55n72 in Handbook of Herbs and Spices: Second Edition . Vol. 1. Elsevier Inc. Radman, R., Saez, T., Bucke, C., & Keshavarz, T. 2003. Elicitation of plants and microbial cell systems. Biotechnology and Applied Biochemistry , 37 (1), 91. https://doi.org/10.1042/ba20020118 Singleton, V. L.; Rossi, J. A. 1965. Colorimetry of Total Phenolics with Phosphomolybdic-Phosphotungstic Acid Reagents. Am. J. Enol. Vitic ., 16 (3), 144n158.