Lipid–protein microdomains (presumably rafts) of the plasmalemma isolated from the beetroots subjected to hyperosmotic stress and hypoosmotic stress were studied. In these microdomains, the variations in the composition of total lipids, sterols, and fatty acids were observed. These variations differed under hypo- and hyperosmotic types of stress. We presumed that such variations were bound up with different strategies, which are probably related to protecting the cell from osmotic stress. One of the protection tendencies might be related, in our opinion, to credible growth of the content of such lipids as sterols and sterol esters, which are considered as raft-forming. Under osmotic stress, these lipids can contribute to the formation of both new raft structures and new membrane contacts of plasmalemma with intracellular organelles. Another protection tendency may be bound up with the redistribution of membrane phospholipids and phosphoglycerolipids possibly to stabilize the membrane’s lamellar structure, which is ensured by credible growth of the content of such lipids as phosphatidylcholines, phosphatidylinositols, and digalactosyldiacylglycerol. The participation of lipid–protein microdomains in the adaptive mechanisms of plant cells may, in our opinion, also be bound up with the redistribution of membrane sterols, which (redistribution) in a number of variants may provoke credible growth in the content of cholesterol or “anti-stress” sterols (campesterol and stigmasterol). So, according to our results, the variations in the content of the plasmalemma lipid–protein microdomains take place under osmotic stress. These variations may influence the functioning of plasmalemma and take part in the adaptive mechanisms of plant cells.

Graphic Abstract

中文翻译：

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浆膜微区（筏）在渗透胁迫下保护植物细胞中的作用

研究了从经受高渗应激和低渗应激的甜菜根中分离的质膜的脂质-蛋白质微结构域（可能是筏）。在这些微区中，观察到总脂质、甾醇和脂肪酸组成的变化。这些变化在低渗和高渗类型的压力下有所不同。我们推测这些变化与不同的策略有关，这可能与保护细胞免受渗透压力有关。在我们看来，保护趋势之一可能与甾醇和甾醇酯等脂质含量的可靠增长有关，这些脂质被认为是形成筏的。在渗透胁迫下，这些脂质有助于形成新的筏状结构和质膜与细胞内细胞器的新膜接触。另一种保护趋势可能与膜磷脂和磷酸甘油脂的重新分布有关，这可能是为了稳定膜的层状结构，这是通过诸如磷脂酰胆碱、磷脂酰肌醇和双半乳糖基二酰基甘油等脂质含量的可靠增长来确保的。在我们看来，脂质-蛋白质微结构域参与植物细胞的适应性机制也可能与膜甾醇的重新分布有关，在许多变体中，它（重新分布）可能会引起胆固醇含量的可信增长或“抗压力”甾醇（菜油甾醇和豆甾醇）。因此，根据我们的结果，质膜脂质 - 蛋白质微结构域含量的变化发生在渗透胁迫下。

图形摘要