Identification and Determination by Fast Atom Bombardment Mass Spectrometry of the Compatible Solute Choline-O-sulfate in Limonium Species and Other Halophytes

Abstract

A sensitive and specific method was developed for determining choline-0-sulfate by fast atom bombardment mass spectrometry, using a deuterium labelled choline-0-sulfate internal standard. This method was used to survey leaves or shoots of 30 native halophytic species from 14 families, collected from temperate and subtropical saline habitats. Twenty-three species had very little choline-0-sulfate (< 1-2 pmol g-' dry wt) but Avicennia germinans contained 8 pmol g-' dry wt, and all six members of the family Plumbaginaceae surveyed (Limonium spp. and Armeria maritima) accumulated > 100 pmol g-' dry wt. Three cultivated Limonium species were also found to accumulate choline-0-sulfate when salinised with NaCl or with NaCl plus Na2S04 under controlled environmental conditions. The identity of choline-0-sulfate in Limonium species was confirmed by high resolution and tandem mass spectrometry, by 'H nuclear magnetic resonance, and by analysis of hydrolysis products. Tests with Limonium leaf disks showed that the salt glands of this genus secrete very little sulfate. Possible roles for choline-0-sulfate in osmotic adjustment and sulfate detoxification are discussed.O3lO-7841/9l/O4O3 l7$OS. OO

Comparative Physiological Evidence that β-Alanine Betaine and Choline-O-Sulfate Act as Compatible Osmolytes in Halophytic Limonium Species

“…Seeds ofLimonium (19). Samples (50 mg) of freeze dried and milled tissue received 448 nmol of dg-glycine betaine, 200 nmol of d9-f3-alanine betaine, and 1000 nmol of d9-choline-O-sulfate and were extracted using the methanol/chloroform/water procedure described previously (7). The aqueous phase from this extraction was fractionated on 1.5-mL columns of Dowex-(OH-) and Dowex-50 (H+) arranged in series.…”

“…Limonium vulgare (Plumbaginaceae) is one example. This species has been shown to contain high levels (>100 umol .g dry weight-') of ,B-alanine betaine (12,20) and choline-O-sulfate (7) when grown in saline conditions. Like glycine betaine, these two compounds exist as zwitterions with zero net charge at physiological pH ( Fig.…”

“…Sensitive and specific FABMS methods (7,17) were used to determine QACs. The surprising finding that various Limonium species accumulate either glycine betaine or #-alanine betaine facilitated a comparative physiological approach.…”

Biosynthesis of 3-Dimethylsulfoniopropionate in Wollastonia biflora (L.) DC. (Evidence That S-Methylmethionine Is an Intermediate)

“…Instrumentation was as described by Hanson and Gage (1991). DMSP was analyzed as the HCl salt, routinely using glycerol as matrix.…”

“…Discs were extracted using a methanol-chloroform-water procedure (Hanson and Gage, 1991) after adding appropriate unlabeled carriers (SMM, MTP, or Met, 0.2-1.0 pmol per nine discs). The aqueous phase was dried at 45 to 5OoC in a stream of N2, dissolved in water, and applied to a series of three 1-mL columns in the order BioRex-70 (H+), Dowex-1 (OH-), Dowex-50 (H+).…”