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Lipid metabolism in the moss Dicranum scoparium : effect of light conditions and heavy metals on the accumulation of acetylenic triacylglycerols
Author(s) -
Guschina Irina A.,
Dobson Gary,
Harwood John L.
Publication year - 2002
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1034/j.1399-3054.2002.1160402.x
Subject(s) - moss , labelling , chemistry , lipid metabolism , metabolism , biochemistry , botany , biology
Lipid metabolism in the moss Dicranum scoparium Hedw. was studied using radiolabelling from [1‐ 14 C]acetate. The effect of two environmental parameters, light and heavy metals, on such metabolism was examined. Radiolabelling was approximately linear for 48 h after which the radioactivity in the total and polar lipid fractions remained constant in the light, whereas it declined in the dark. Pulse‐chase experiments confirmed that lipid labelling was influenced by light exposure. Light exposure altered the pattern of polar lipid labelling, especially of those lipids associated with chloroplast membranes. Within the neutral lipids, diacylglycerols and triacylglycerols (TAGs) were the major classes labelled. D. scoparium contained up to 45% of total acyl moieties as 9,12,15‐octadecatrien‐6‐ynoic (18:3A) acid and this was found in a TAG subfraction which could be separated by TLC. Although TAGs always represented 65–75% of total neutral lipid labelling, the proportion of TAGs containing 18:3A was increased with time and by light but reduced by exposure to environmentally relevant levels of Cu 2+ and Pb 2+ . The data suggest that 18:3A is produced in D. scoparium by the action of a bi‐functional Δ6‐desaturase on α ‐linolenate. Furthermore, important environmental factors (such as light and heavy metals) significantly change the metabolism of TAGs containing 18:3A.