How do background ozone concentrations affect the biosynthesis of rosmarinic acid in Melissa officinalis?
Lemon balm (Melissa officinalis; Lamiaceae) plants were exposed to background ozone (O3) dosages (80ppb for 5h), because high background levels of O3 are considered to be as harmful as episodic O3 peaks. Immediately at the end of fumigation the plants appeared visually symptomless, but necrotic lesions were observed later. The biosynthesis of rosmarinic acid (RA) comprises eight enzymes, among them phenylalanine ammonia-lyase (PAL), 4-coumarate:coenzyme A ligase (4CL), tyrosine aminotransferase (TAT) and rosmarinic acid synthase (RAS). The transcript levels of these genes have been investigated by quantitative RT-PCR. There was a quick up-regulation of all genes at 3h of O3 exposure, but at 24h from beginning of exposure (FBE) only RAS and PAL were up-regulated. The specific activity of RAS was closely correlated with a decrease of RA concentration in lemon balm leaves. The specific activity of PAL increased at 12h FBE to 163% in comparison to control levels. This work provides insight into the effect of O3 stress on the formation of the main phenolic ingredient of the pharmaceutically important plant M. officinalis.
Institut für Pharmazeutische Biologie und Biotechnologie, Philipps-Universität Marburg, Deutschhausstr. 17A, D-35037 Marburg, Germany.
Anne S
AS
Döring
Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, I-56124 Pisa, Italy.
Elisa
E
Pellegrini
Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, I-56124 Pisa, Italy.
Michele
M
Della Batola
Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, I-56124 Pisa, Italy.
Cristina
C
Nali
Department of Agriculture, Food and Environment, University of Pisa, Via del Borghetto 80, I-56124 Pisa, Italy.
Giacomo
G
Lorenzini
Institut für Pharmazeutische Biologie und Biotechnologie, Philipps-Universität Marburg, Deutschhausstr. 17A, D-35037 Marburg, Germany. Electronic address: petersen@staff.uni-marburg.de.
Maike
M
Petersen
D002934:Cinnamates / Q000378:metabolism*; D053630:Depsides / Q000378:metabolism*; D005786:Gene Expression Regulation; D031334:Melissa / Q000235:genetics* / Q000378:metabolism; D018384:Oxidative Stress; D010126:Ozone / Q000378:metabolism*; D010788:Photosynthesis; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000097123:Rosmarinic Acid
D002934:Cinnamates; D053630:Depsides; D010126:Ozone; D010940:Plant Proteins; D000097123:Rosmarinic Acid
Air pollution; Expression analysis; Lemon balm; Rosmarinic acid; qRT-PCR