期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1990
卷号：87
期号：17
页码：6532-6536
DOI：10.1073/pnas.87.17.6532
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Osmotic levels in the range typically used during plant protoplast isolation and incubation were investigated with regard to effects on the lateral diffusion of lipid probes in the plasma membrane. The lateral diffusion coefficient of a fluorescent sterol probe in the plasma membrane of maize (Zea mays L.) root protoplasts in a medium containing 0.45 M mannitol was 4 times faster than when the medium contained 0.9 M mannitol. The lateral diffusion coefficient of a fluorescent phospholipid probe, however, did not change over this range of mannitol concentrations. Similar diffusion characteristics were observed when the medium contained trehalose instead of mannitol. Slower lateral diffusion of the sterol probe at higher osmolality was also observed when KCl/CaCl2-based osmotic media were used with protoplasts isolated by a mechanical, rather than by an enzymic, method. Extraction and quantitation of total lipids from protoplasts showed that both the phospholipid and sterol contents per protoplast decreased with increasing osmolality, while the sterol/phospholipid ratio increased. These results demonstrate that osmotic stress induces selective changes in both the composition and biophysical properties of plant membranes.
