The Pseudomonas phytotoxin coronatine mimics octadecanoid signalling molecules of higher plants

Abstract

The phytotoxic principle, coronatine, which is present in several pathovars of the plant pathogen, Pseudomonas syringae was shown to be highly active in completely different, jasmonate-selective bioassays. At nanomolar to micromolar concentrations, coronatine induced the accumulation of defense-related secondary metabolites in several plant cell cultures, induced transcript accumulation of the elicitor-responsive gene encoding the berberine bridge enzyme of Eschscholtzia califomica, as well as the coiling response of Bryonia dioica tendrils. Biological activity critically depended upon the structure of coronatine, and slight moditications, such as methylation of the carboxyl moiety or reduction of the carbonyl group, rendered the molecules almost inactive. Coronafacic acid, obtained by hydrolysis of coronatine, was also nearly inactive. Coronatine did not elicit the accumulation of endogenous jasmonic acid in the systems analyzed. While coronafacic acid is similar in structure to jasmonic acid, we found coronatine to be a close structural analogue of the cyclic Cl&precursor of jasmonic acid, lZoxo-phytodienoic acid. The phytotoxic symptoms produced by coronatine can now be understood on the basis of the toxin's action as a mimic of the octadecanoid signalling molecules of higher plants.

The Role of Octadecanoids and Functional Mimics in Soybean Defense Responses

“…The phytotoxin coronatine, produced by several pathovars of Pseudomonas syringae, induced reactions similar to OPDA (Blechert et al, 1999;Koch et al, 1999). Therefore, coronatine is suggested to represent a structural analogue of OPDA (Weiler et al, 1994). Deduced from the structure of coronatine, new synthetic analogs of OPDA have been designed which were expected to mimic OPDA and/or jasmonate activities.…”

Amino acid conjugates of jasmonic acid induce jasmonate‐responsive gene expression in barley (Hordeum vulgare L.) leaves

“…Furthermore, (-)-JA (1) was shown to occur conjugated with a variety of amino acids in higher plants [2,3]. Several environmental stresses like wounding [4][5][6], electric current application [7], osmotic stress [8], mechanical stress [9] or local burning [7] lead to an endogenous rise of jasmonates, thereby inducing synthesis of specific proteins like proteinase inhibitors in tomato or vegetative storage proteins in soybean (for review cf. [10]).…”

“…Jasmonate-induced events such as the biosynthesis of glucosinolates [15], ethylene formation [16], tendril coiling [9], or the emission of volatiles [17] were also induced upon treatment with coronatine which can be regarded as an analogue of JA amino acid conjugates [18]. Coronatine is a phytotoxin produced by several pathovars of Pseudomonas syringae, and *Corresponding author.…”

“…Fax: (49) 345-5582-162. E-mail : cwastern@ipb.uni-halle.de is up to 100-fold more active than JA (1,2,8) or JM (7) in several JA-responsive events [9,19].…”

Effects of Coronatine on Growth, Gas Exchange Traits, Chlorophyll Content, Antioxidant Enzymes and Lipid Peroxidation in Maize (Zea mays L.) Seedlings under Simulated Drought Stress

“…Previous research results indicated that coronatine mimics a precursor of jasmonic acid (JA) which is involved in the biological processes of plant growth and development (Sakai, 1980(Sakai, , 1981Sakai et al, 1984;Ferguson and Mitchell, 1985;Mino et al, 1987;Kenyon and Turner, 1990;Weiler et al, 1993Weiler et al, , 1994. Coronatine affects the accumulation of defenserelated secondary metabolites such as pterocarpantype glyceollin, sakuranetin, momilactone A, alkaloid, volatile materials and taxol (Ichihara and Toshima, 1998;Tamogami and Kodama, 2000;Fliegmann et al, 2003;Lauchli and Boland, 2003).…”