DISCOVERY OF THE PRESENCE OF 3-DIMETHYLSU LFONIOPROPRIONATE IN SEVERAL SPECIES OF ANGIOSPERMS

3-Dimethylsulfoniopropionate (DMSP) is an osmoprotectant compound that serves as the biogenic precursor of dimethyl sulfide (DMS), an import ant atmospheric sulfur gas. DMSP is known to be accumulated by many ma rine algae but has been little studied in higher plants; it has previo usly been identified in only four angiosperm genera (one genus from th e Asteraceae and three from the Poaceae), at levels of about 5 to 30 m u mol g(-1) fresh weight. Leaves of 177 species of angiosperms represe nting 90 families from 55 orders were screened for DMSP. An indirect a ssay 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 mu mol g(-1) fresh weight. Twenty-nine species (from 22 families and 22 orders) had detectable levels of DMSP , all fairly low (less than or equal to 1 mu mol g(-1) fresh weight). In vivo radiotracer labeling results indicated that species from the A steraceae, Poaceae, and Rosaceae containing DMSP synthesize it from me thionine via S-methylmethionine, and that this pathway may be present at a low level in species of Asteraceae that do not accumulate detecta ble amounts of DMSP. Taken together, these data imply that the capacit y for DMSP production is widespread among Angiosperms.