Évidence en faveur de la présence du 3-diméthylsulfoniopropionate chez une large gamme d'Angiospermes
3-Dimethylsulfoniopropionate (DMSP) is an osmoprotectant compound that serves as the biogenic precursor of dimethyl sulfide (DMS), an important atmospheric sulfur gas. DMSP is known to be accumulated by many marine algae but has been little studied in higher plants; it has previously been identified in only four angiosperm genera (one genus from the Asteraceae and three from the Poaceae), at levels of about 5 to 30 μmol g−1 fresh weight. Leaves of 177 species of angiosperms representing 90 families from 55 orders were screened for DMSP. An indirect assay was used in which DMSP treated with a cold NaOH solution released acrylic acid and DMS, the latter being analyzed by gas chromatography. The detection limit was 0.01 μmol g−1 fresh weight. Twenty-nine species (from 22 families and 22 orders) had detectable levels of DMSP, all fairly low (≤ 1 μmol g−1 fresh weight). In vivo radiotracer labeling results indicated that species from the Asteraceae, Poaceae, and Rosaceae containing DMSP synthesize it from methionine via S-methylmethionine, and that this pathway may be present at a low level in species of Asteraceae that do not accumulate detectable amounts of DMSP. Taken together, these data imply that the capacity for DMSP production is widespread among Angiosperms. Key words: 3-dimethylsulfonioproprionate, S-methylmethionine, dimethyl sulfide.