Characterization of glucosylceramides in the Polygonaceae, Rumex obtusifolius L. injurious weed.

Rumex obtusifolius L., a member of Polygonaceae, is one of the world's worst weeds. We characterized the glucosylceramide molecular species in leaves of R. obtusifolius by liquid chromatography/tandem mass spectrometry. 4,8-Sphingadienines were principally paired with 2-hydroxy palmitic acids. In contrast, 4-hydroxy-8-sphingenines were chiefly attached to 2-hydroxy fatty acids with 22 to 26 carbon-chain length. A unique characteristic of the 2-hydroxy fatty acid composition of R. obtusifolius was the high content of n-9 monoenoic 2-hydroxy fatty acids with 22 and 24 carbon-chain length. The levels of the Z and E stereoisomers of the 8-unsaturated long-chain bases were reliably distinguished from those in other plant families in ten species of Polygonaceae.