DOI: 10.1002/cbic.200500365 Phospholipases and Galactolipases Trigger Oxylipin-Mediated Wound-Activated Defence in the Red Alga Gracilaria chilensis against Epiphytes Ulrich Lion, [a] Theresa Wiesemeier, [a, b] Florian Weinberger, [c] Jessica Beltrµn, [d] Verónica Flores, [d] Sylvain Faugeron, [d] Juan Correa, [d] and Georg Pohnert* [a, b] Introduction Cultivation of the marine red alga Gracilaria chilensis C. J. Bird, McLachlan & E. C. Oliveira for the production of agar hydrocol- loids is a major asset of Chilean aquaculture. More than 500 farming operations are established across the country, with annual yields of over 120000 wet metric tons. [1] A main nui- sance to farmers is the widespread occurrence of infections by algal epiphytes, which negatively affect crop growth rate, lead to biomass losses due to increased drag and result in products with lower economic value. [1–3] Interactions of G. chilensis with competing, parasitic epiphytic or endophytic algae are only poorly understood, which prevents strain selection for opti- mum resistance in aquaculture. Phenomenology of settlement, attachment and germination of epiphytic algal spores has been studied in a number of spe- cies down to the ultrastructural level, [4,5] but the early chemical and biochemical events during the colonization of algal hosts are not well understood. In several cases it has been demon- strated that metabolites from macroalgae can reduce the number of settled algal spores and that physical properties of nontoxic algal surfaces can influence their colonization. [6–8] Most approaches have focused on the activity of tissue ex- tracts and a mechanistic investigation of alga–epiphyte inter- actions has rarely been performed. [9] Depending on the species, epiphytes can either interact with the cell-wall surface or penetrate into the host organism, which results in membrane and cell-wall disruption (P. Leonar- di, J. Correa, personal communication). Here we describe chemical and biochemical processes that occur in G. chilensis after cell damage. We show that G. chilensis reacts upon such tissue damage with the fast release of free fatty acids and the production of oxylipins that include hydroxylated eicosanoic fatty acids. Two epiphytic red algae, Acrochaetium sp. and Ce- ramium rubrum, were used as models to test whether up-regu- lated metabolites modulate chemical defence in G. chilensis. Results and Discussion To monitor the physiological reaction of G. chilensis to tissue damage a protocol was established for the comparison of met- [a] Dr. U. Lion, T. Wiesemeier, Prof. Dr. G. Pohnert Max-Planck-Institute for Chemical Ecology Hans-Knçll-Strasse 8, 07745 Jena (Germany) [b] T. Wiesemeier, Prof. Dr. G. Pohnert Present address: Ecole Polytechnique FØdØrale de Lausanne (EPFL) Institute of Chemical Sciences and Engineering 1015 Lausanne (Switzerland) Fax: (+ 41)21-693-9305 E-mail: Georg.Pohnert@epfl.ch [c] Dr. F. Weinberger Station Biologique de Roscoff UMR 7139 CNRS-UPMC & LIA-DIAMS B.P. 74, 29682 Roscoff Cedex (France) [d] J. Beltrµn, V. Flores, Dr. S. Faugeron, Prof. Dr. J. Correa Departamento de Ecología and Centre for Advanced Studies in Ecology and Biodiversity Facultad de Ciencias Biológicas, P. Universidad Católica de Chile Casilla 114-D, Santiago CP 6513677 (Chile) We investigated the wound response of the commercially impor- tant red alga, Gracilaria chilensis, in order to obtain insight into its interaction with epiphytic pests. After wounding, the host re- leases free fatty acids as well as the hydroxylated eicosanoids, 8R-hydroxy eicosatetraenoic acid (8-HETE) and 7S,8R-dihydroxy eicosatetraenoic acid (7,8-di-HETE). While the release of free arachidonic acid and subsequent formation of 8-HETE is control- led by phospholipase A, 7,8-di-HETE production is independent of this lipase. This dihydroxylated fatty acid might be directly re- leased from galactolipids. Physiologically relevant concentrations of oxylipins reduced spore settlement of Acrochaetium sp. (Rho- dophyta, Acrochaetiaceae) and suppressed the development of hapteria in Ceramium rubrum (Rhodophyta, Ceramiaceae) when these model epiphytes were exposed to artificial surfaces that contained 8-HETE or 7,8-di-HETE. Thus, the immediate re- lease of oxylipins can be seen as G. chilensis defence against epiphytes. ChemBioChem 2006, 7, 457 – 462 # 2006 Wiley-VCH Verlag GmbH&Co. KGaA, Weinheim 457