The jasmonate pathway is involved differentially in the regulation of different defence responses in tobacco cells |
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Authors: | M Rickauer W Brodschelm A Bottin C Véronési H Grimal M T Esquerré-Tugayé |
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Institution: | Centre de Physiologie Végétale, UMR UPS-CNRS 5546, Université Paul Sabatier, 118 route de Narbonne, F-31062 Toulouse Cedex, France, FR Lehrstuhl für Pharmazeutische Biologie, Universit?t München, Karlstrasse 29, D-80333 München, Germany, DE
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Abstract: | Jasmonic acid, a product of the lipoxygenase (LOX) pathway, has been proposed to be a signal transducer of defence reactions
in plants. We have reported previously that methyl jasmonate (MJ) induced accumulation of proteinase inhibitors in tobacco
cell suspensions (Rickauer et al., 1992, Plant Physiol Biochem 30: 579–584). The role of this compound in the induction of
this and of other defence reactions is further studied in this paper. Treatment of tobacco cell suspensions with an elicitor
from Phytophthora parasitica var. nicotianae induced a rapid and transient increase in jasmonic acid levels, which was abolished when cells were preincubated with eicosatetraynoic
acid (ETYA), an inhibitor of LOX. Pretreatment with ETYA also inhibited the induction of proteinase inhibitors by fungal elicitor,
but not by MJ. Linolenic acid, a precursor of jasmonate biosynthesis, induced this defence response, whereas linoleic acid
had no effect. Expression of defence-related genes encoding proteinase inhibitor II, hydroxyproline-rich or glycine-rich glycoproteins,
glucanase and chitinase, was induced in a basically similar manner by fungal elicitor or MJ. However, ETYA did not inhibit,
or only partially inhibited, the elicitation of these defence genes. Expression of the sesquiterpene cyclase (5-epi-aristolochene synthase) gene was not induced by MJ, but only by fungal elicitor, and ETYA pretreatment had no effect on this
induction. The obtained results indicate that synthesis of jasmonate via the LOX pathway seems to be only part of a complex
regulatory mechanism for the onset of many, but not all, defence reactions.
Received: 4 July 1996 / Accepted: 23 November 1996 |
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Keywords: | : Defence reaction Elicitor Jasmonate Lipoxygenase Nicotiana Signal transduction |
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