Seasonal changes in leaf lipids of Diapensia lapponica, with special reference to storage lipid bodies

Abstract

Seasonal fluctuations in storage lipids in the cushion plant Diapensia lapponico, growing in Northern Finland (70"N 27"E). were studied by microscopy and chemical analysis. Lipid bodies in the mesophyll cells were stained with Sudan Black for quantitative observation by light microscope. Electron microscope observations were made using aldehyde prefixed and osmium tetroxide postfixed sections of leaf blades. Thin layer and gas capillary chromatographic techniques were used to analyse total lipids and total fatty acids in green shoots of Diapensia. Free sugars and starch were extracted scparately and determined by the anthrone method. A mesophyll cell was characterized by a large lipid body (storage lipid) in summer hut by several small spherules in winter. Total surface area of the cross-sectioned lipid globules was at its lowest from April to September; the maximal value was in March.The amount of total lipids in the leafy tops of D. lapponica was 91-200 mg g-' dry weight. Values were lowest at the end of June, when the total carbohydrate level was at its highest. Accordingly, the decrease in the total lipid level in the early growing season, when new leaves were developing, can be attributed primarily to the increase in the level of carbohydrates, particularly starch. The amount of total fatty acids varied from 21 to 30 mg g-' dry weight. The level increased in the early growing season and remained elevated throughout the summer. Like the total lipids, the total fatty acids arc derived from structurally different parts of the sclerophyllous leaves, including the well-developed cuticle and epicuticular wax layer. The discrepancies in the results obtained from microscopic and chemical analyses arc discussed.

Oil bodies in leaf mesophyll cells of angiosperms: overview and a selected survey

“…Pihakaski et al (1987) reviewed some of the literature about this and showed that a sclerophyllous, evergreen cushion plant of arctic and subarctic regions, Diapensia lapponica (Diapensiaceae), has a single large lipid body in each mesophyll cell during warmer months, but many smaller lipid bodies per mesophyll cell during cold months. They speculated that this change helps to lower the freezing point of cells.…”

Impact of Seawater Salinity on Ultrastructure of Chloroplasts and Oleosomes in Relation to Fat Metabolism in Flag Leaf of Two Wheat Cultivars During Grain-filling

“…Also, it was thought possible that they might function as short-term storage of photosynthetic products where assimilates being stored in them during periods of peak photosynthesis and metabolized, for example, during the night [4]. Another possible function for oleosomes is adaptation to environmental stress such as salinity [5], cold temperature [6] and fungal infection [3].…”

Oil Bodies and Oleosins in Physcomitrella Possess Characteristics Representative of Early Trends in Evolution

“…Only the moss Physcomitrella patens (three paralogs) and the primitive fern (fern ally; Selaginella moellendorffii; eight paralogs) possess genes encoding oleosins. Primitive plants, including bryophytes (mosses) and ferns, contain neutral lipids and OBs (Swanson et al, 1976;Pihakaski et al, 1987;Dembitsky, 1993). We chose the more primitive Physcomitrella for intensive study.…”