Conserved and species-specific oxylipin pathways in the wound-activated chemical defense of the noninvasive red alga Gracilaria chilensis and the invasive Gracilaria vermiculophylla

Abstract

SummaryChemical defense of the invasive red alga Gracilaria vermiculophylla has been studied and compared to that of the noninvasive but related Gracilaria chilensis. Both species rely on a wound-activated chemical defense that makes them less attractive to the herbivorous sea snail Echinolittorina peruviana. The chemical stress response of both species was monitored by LC–ESIMS-based metabolic profiling and revealed commonalities and differences. Both algae rely on a rapid lipoxygenase mediated transformation of arachidonic acid to known and novel oxylipins. Common products are 7,8-dihydroxyeicosatetraenoic acid and a novel eicosanoid with an unusual γ-lactone moiety. Several prostaglandins were predominantly formed by the invasive species. The role of some of these metabolites was investigated by surveying the attachment of E. peruviana on artificial food containing the respective oxylipins. Both algae species are defended against this general herbivore by 7,8-dihydroxyeicosatetraenoic acid, whereas the prostaglandins and the novel oxylipins were inactive at naturally occurring concentrations. The role of different oxylipins in the invasive potential of Gracilaria spp. is discussed.

Lipid Classes, Fatty Acid Composition, and Glycerolipid Molecular Species of the Red Alga <i>Gracilaria vermiculophylla</i>, a Prostaglandin-Producing Seaweed

“…The sum of the major four glycerolipids of G. vermiculophylla accounted for 43.0 of the total lipid profile, the contents of which mg/g of total lipids SD of three analyses were in the order of DGDG 123. 7 6 , whereas SQDG contained a large amount of saturated fatty acid SFA 79. 1 .…”

“…Algal prostaglandins are produced from glyceroglycolipid GL and phospholipid PL substrates, which are hydrolyzed by acyl-hydrolases that are activated by physical wounding 4,6,7,13 . Wounding releases arachidonic acid 20:4n-6 or eicosapentaenoic acid 20:5n-3 , which are then transformed to prostaglandins by the action of COXs classes, fatty acid composition, and glycerolipid molecular species of the alga were clarified using two-dimensional thin-layer chromatography 2D-TLC , gas chromatography GC , high-performance liquid chromatography HPLC , and mass spectrometry MS .…”

Invasion success of the seaweed Gracilaria vermiculophylla correlates with low palatibility

“…G. vermiculophylla is able to defend itself from feeding by up-regulation of chemical compounds. After wounding, the alga produces -among other substances -arachidonic acid derivates, which were found to deter mesograzers such as the omnivorous isopod Idotea baltica (Nylund et al 2011) or the herbivorous sea snail Echinolittorina peruviana (Rempt et al 2012). It seems likely that these or other substances also act as feeding deterrents against L. brevicula and L. littorea.…”

“…Also, Gracilaria vermiculophylla is capable of defending itself from herbivory by mesograzers: if tissue is damaged -either by artificial mechanical wounding or by grazing -the alga produces oxylipins (Nylund et al 2011, Rempt et al 2012). These compounds deter potential grazers of G. vermiculophylla, such as the omnivorous isopod Idotea balthica (Nylund et al 2011) or the herbivorous sea snail Echinolittorina peruviana (Rempt et al 2012). Wound-activated oxylipins are also molecular messengers that mediate induced defenses of gracilarioids (Wein berger et al 2011).…”

Gracilaria vermiculophylla in the Virginia Coastal Bays: Documenting the Distributionand Effects of a Non-Native Species

“…vermiculophylla tissue (Nylund et al 2011;Rempt et al 2012) make the macroalga unpalatable to herbivores who often choose to consume native macroalgae (Thomsen & McGlathery 2007;Nejrup & Pedersen 2010;Jensen et al 2011;.…”