title: Adaptive changes in photosynthetic performance and secondary metabolites during white dead nettle micropropagation.
abstract: The white dead nettle, Lamium album L., is an herb that has been successfully cultivated under in vitro conditions. The L. album micropropagation system offers a combination of factors (light intensity, temperature, carbon dioxide (CO2) level, humidity) that are limiting for plant growth and bioactive capacity. To get a better understanding of the mechanism of plant acclimation towards environmental changes, we performed a comparative investigation on primary and secondary metabolism in fully expanded L. album leaves during the consecutive growth in in situ, in vitro, and ex vitro conditions. Although the genetic identity was not affected, structural and physiological deviations were observed, and the level of bioactive compounds was modified. During in vitro cultivation, the L. album leaves became thinner with unaffected overall leaf organization, but with a reduced number of palisade mesophyll layers. Structural deviation of the thylakoid membrane system was detected. In addition, the photosystem 2 (PS2) electron transport was retarded, and the plants were more vulnerable to light damage as indicated by the decreased photoprotection ability estimated by fluorescence parameters. The related CO2 assimilation and transpiration rates were subsequently reduced, as were the content of essential oils and phenolics. Transfer of the plants ex vitro did not increase the number of palisade numbers, but the chloroplast structure and PS2 functionality were recovered. Strikingly, the rates of CO2 assimilation and transpiration were increased compared to in situ control plants. While the phenolics content reached normal levels during ex vitro growth, the essential oils remained low. Overall, our study broadens the understanding about the nature of plant responses towards environmental conditions.
authors.affiliation: Department of Plant Physiology, Faculty of Biology, Sofia University "St. Kliment Ohridski", 8 Dragan Tsankov Blvd., 1164 Sofia, Bulgaria.
authors.forename: V
authors.initials: V
authors.lastname: Kapchina-Toteva
authors.affiliation: Department of Plant Physiology, Faculty of Biology, Sofia University "St. Kliment Ohridski", 8 Dragan Tsankov Blvd., 1164 Sofia, Bulgaria.
authors.forename: M A
authors.initials: MA
authors.lastname: Dimitrova
authors.affiliation: Department of Botany, Faculty of Biology, Sofia University "St. Kliment Ohridski", 8 Dragan Tsankov Blvd., 1164 Sofia, Bulgaria.
authors.forename: M
authors.initials: M
authors.lastname: Stefanova
authors.affiliation: Department of Botany, Faculty of Biology, Sofia University "St. Kliment Ohridski", 8 Dragan Tsankov Blvd., 1164 Sofia, Bulgaria.
authors.forename: D
authors.initials: D
authors.lastname: Koleva
authors.affiliation: AgroBioInstitute, Buld. Dragan Tzankov 8, 1164 Sofia, Bulgaria.
authors.forename: K
authors.initials: K
authors.lastname: Kostov
authors.affiliation: Department of Plant Physiology, Faculty of Biology, Sofia University "St. Kliment Ohridski", 8 Dragan Tsankov Blvd., 1164 Sofia, Bulgaria.
authors.forename: Zh P
authors.initials: ZhP
authors.lastname: Yordanova
authors.affiliation: Department of Biophysics, Faculty of Biology, Sofia University "St. Kliment Ohridski", 8 Dragan Tsankov Blvd., 1164 Sofia, Bulgaria.
authors.forename: D
authors.initials: D
authors.lastname: Stefanov
authors.affiliation: Department of Plant Physiology, Faculty of Biology, Sofia University "St. Kliment Ohridski", 8 Dragan Tsankov Blvd., 1164 Sofia, Bulgaria. Electronic address: miroslava_zhiponova@abv.bg.
authors.forename: M K
authors.initials: MK
authors.lastname: Zhiponova
mesh_terms: D000222:Adaptation, Physiological; D002245:Carbon Dioxide / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism; D004579:Electron Transport; D005419:Flavonoids / Q000378:metabolism; D005453:Fluorescence; D062385:Hydroxybenzoates / Q000378:metabolism; D019686:Lamiaceae / Q000235:genetics / Q000502:physiology* / Q000528:radiation effects / Q000648:ultrastructure; D008027:Light; D009822:Oils, Volatile / Q000378:metabolism*; D010788:Photosynthesis / Q000502:physiology*; D045332:Photosystem II Protein Complex / Q000378:metabolism*; D018515:Plant Leaves / Q000235:genetics / Q000502:physiology / Q000528:radiation effects / Q000648:ultrastructure; D010938:Plant Oils / Q000378:metabolism*; D018526:Plant Transpiration / Q000502:physiology; D010946:Plants, Medicinal; D011003:Ploidies; D013696:Temperature; D020524:Thylakoids / Q000378:metabolism
chemical_list: D005419:Flavonoids; D062385:Hydroxybenzoates; D009822:Oils, Volatile; D045332:Photosystem II Protein Complex; D010938:Plant Oils; D002734:Chlorophyll; D002245:Carbon Dioxide; C017616:phenolic acid
keywords: Leaf; Medicinal plants; Micropropagation; Photosynthesis; Secondary metabolites