Variability in dimethylsulfoniopropionate (DMSP) concentrations in Spartina alterniflora and the effect on Littoraria irrorata

Abstract

We measured concentrations of dimethylsulfoniopropionate (DMSP) in Spartina alterni- flora (Loisel.) in response to the plant hormones abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) to determine whether DMSP concentration is linked to any of their signaling pathways. DMSP concentrations were also measured in plants at a salt marsh dieback site in Georgetown County, South Carolina (USA), to determine whether dieback conditions affect foliar DMSP concen- trations. We found elevated levels of DMSP in plants receiving SA treatment compared to a control treatment, but we found no treatment effect for either of the other 2 hormone treatments. This sug- gests that DMSP production or transformation is linked to the SA signaling pathway. Diminished lev- els of DMSP were observed in plants nearest the dieback edge compared to those farthest from the dieback in an apparently healthy marsh, which suggests that DMSP concentration responds to envi- ronmental conditions connected with salt marsh dieback. Using a ring assay, we found that Littoraria irrorata snails, potential herbivores of S. alterniflora, were attracted to DMSP. However, we found no correlation between DMSP concentration and L. irrorata density at the acute dieback site. These results suggest that factors such as plant biomass may play a more important role than DMSP in determining L. irrorata distribution in dieback areas.