Lipid metabolism of a Tertiary relic species, Kerguelen cabbage (Pringlea antiscorbutica)

Abstract

The Kerguelen cabbage, Pringlea antiscorbutica R. Br., is a Tertiary relic Cruciferous species well adapted to the continuous cold conditions of this subantarctic archipelago. Each shoot exhibits all the steps of differentiation from embryonic leaves (1 mm) to mature leaves (30–40 cm). In the mature leaf, the chlorophyllous part is often reduced to a narrow peripheral strip, the chloroplasts being replaced progressively by amyloplasts toward the leaf center. This particular situation led us to compare the overall polar lipid and fatty acid composition from the green part of the mature leaves with those of the undifferentiated leaves, without chloroplasts. These lipid compositions are identical with those of all the C16:3 plants analyzed to date. The only feature characteristic of a chilling-resistant plant is the high percentage of saturated phosphatidylglycerol (16:0 + 16:1t). Polar lipid synthesis was followed by direct injection of [14C]acetate into the immature leaves. The incorporations of [14C]acetate into phosphatidylcholine and monogalactosyldiacylglycerol fatty acids closely parallel each other and there is no indication of fatty acid transfer from phosphatidylcholine to monogalactosyldiacylglycerol.