Fruehe Reaktionen von Tabak und Buche auf Ozon: Induktion des Tyramin- und Polyaminstoffwechsels

The thesis deals with the physiological reaction of plants - especially tobacco and beech, but also spruce and pine - to experimental ozone fumigation. Attention is focused on the accumulation of tyramine and putrescine derivatives in leaves. The activity of the synthetizing enzymes (cinnamic alcohol dehydrogenase - CAD - and pheylamine ammonium lyase) and of peroxidases is determined, their activity distributions in the plants and conversion rates (of C-14-labelled tyramine) are measured, and associations with visible ozone damage (necroses) are investigated. Some enzyme tests are carried through in vitro. The investigations lead to the conclusion that the inducement of tyramine metabolism in plants is an important and very early reaction to ozone. It is independent of necrosis formation but leads to changes in the cell walls owing to the inclusion of lignin-like tyramine conjugates. (orig.)Diese Dissertation beschaeftigt sich mit der physiologischen Reaktion von Pflanzen - insbesondere Tabak und Buche, aber auch Fichte und Kiefer - auf experimentelle Begasung mit Ozon. Dabei wird das Hauptaugenmerk auf die Anreicherung von Tyramin- und Putrescinderivaten in Blaettern gerichtet. Die Aktivitaet der synthetisierenden Enzyme (der Zimtalkohol-Dehydrogenase (CAD) und der Phenylalanin-Ammoniak-Lyase) und von Peroxidasen wird bestimmt, die Verteilung ihrer Aktivitaet in der Pflanze und die Umsetzungsraten (von "1"4C-markiertem Tyramin) gemessen und Zusammenhaenge mit sichtbaren Ozonschaeden (Nekrosen) untersucht. Einige in vitro-Enzymtests werden durchgefuehrt. Aus den Untersuchungen wird gefolgert, dass die Induktion des Tyraminstoffwechsels eine wichtige und sehr fruehe Reaktion der Pflanzen auf Ozon ist. Sie ist unabhaengig von der Nekrosenbildung, fuehrt aber zu einer Veraenderung der Zellwand durch Einlagerung ''ligninaehnlicher'' Tyraminkonjugate. (orig./UWA)Available from TIB Hannover: G93/609 / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Ozone-induced Changes of mRNA levels of ß-1,3-glucanase, Chitinase and 'Pathogenesis- related' Protein 1b in Tobacco Plants.

Treatment of the ozone-sensitive tobacco cultivar Bel W3 with an ozone pulse (0.15 microliter/l, 5 h) markedly increased the mRNA level of basic beta-1,3-glucanase and to a lower degree that of basic chitinase. The increase of beta-1,3-glucanase mRNA level occurred within 1 h and showed a transient maximum. Seventeen hours after ozone treatment, the beta-1,3-glucanase mRNA level decreased to lower values. The increase of basic chitinase mRNA level was delayed and was less pronounced than that of beta-1,3-glucanase mRNA. Cultivar Bel B showed only a small increase of beta-1,3-glucanase mRNA level after the same ozone treatment, whereas its basic chitinase mRNA was more strongly induced. Prolonged ozone treatment for 2 days of tobacco Bel W3 led to a persistent level of beta-1,3-glucanase and basic chitinase mRNAs, as well as to an increase of acidic chitinase and 'pathogenesis-related' (PR) 1b mRNA levels. The results indicate that genes so far considered to code for PR proteins may also be involved in the plant response to oxidative stress