No Evidence for the Induction of Brown Algal Chemical Defense by the Phytohormones Jasmonic Acid and Methyl Jasmonate

Abstract

Induced chemical defense reactions are widespread in marine brown algae. Despite the evidence that the biosynthesis of defense metabolites can be up-regulated upon herbivory, we do not know how this regulation of biosynthetic pathways to secondary metabolites is achieved in brown algae. In higher plants, the phytohormone jasmonic acid (JA) is crucial for the mediation of induced chemical defenses, and several findings of this metabolite from marine sources have been reported. We tested the hypothesis that JA or related metabolites play a role in induced brown algal defense. Quantification of oxylipins with a detection limit around 20 ng g −1 algal tissue did not reveal the presence of JA in the seven examined brown algal species Dictyota dichotoma, Colpomenia peregrina, Ectocarpus fasciculatus, Fucus vesiculosus, Himanthalia elongata, Saccharina latissima (formerly Laminaria saccharina), and Sargassum muticum. Moreover, treatment with ecologically relevant concentrations of JA and methyl jasmonate did not lead to a significant change in the profile of medium-and non-polar metabolites of the tested algae.Only when high concentrations of ≥500 μg ml −1 medium of the phytohormones were applied that a metabolic response which could be attributed to unspecific stress was observed.Bioassays with D. dichotoma that focused on medium-and non-polar compounds confirmed the lack of a biological role of JA and methyl jasmonate in the induction of algal induced chemical defenses. The phytohormone-treated samples did not exhibit any increased defense potential towards the amphipod Ampithoe longimana and the isopod Paracerceis caudata. JA and related phytohormones, known to be active in higher plants, thus appear to play no role in brown algae for induction of the defense chemicals studied here.

Prostaglandin A2triggers a strong oxidative burst in Laminaria: a novel defense inducer in brown algae?

“…In comparison, plants with these studies, Wiesemeier et al (2008) did not observe defense-related effects of jasmonate in other species of brown algae.…”

The effects of abscisic acid, salicylic acid and jasmonic acid on lipid accumulation in two freshwater <i>Chlorella</i> strains

“…Gao et al (2012a) also reported that JA was an effective regulator that stimulated astaxanthin production in H. pluvialis. However, it appeared to play no role in brown algae for defense induction (Wiesemeier et al, 2008).…”

IMPACTS OF MESOGRAZERS ON EPIPHYTE AND ENDOPHYTE GROWTH ASSOCIATED WITH CHEMICALLY DEFENDED MACROALGE FROM THE WESTERN ANTARCTIC PENINSULA: A MESOCOSM EXPERIMENT1

“…Some studies have indicated that algae experiencing increased abiotic stresses are less likely to produce chemical deterrents (Renaud et al. 1990, Wiesemeier et al. 2008).…”