Chen Hui, Jiang Jian-Guo
College of Food and Bioengineering, South China University of Technology, Guangzhou, China.
J Cell Physiol. 2009 May;219(2):251-8. doi: 10.1002/jcp.21715.
Some species in genus Dunaliella are unique in their remarkable abilities to accumulate large numbers of beta-carotene and thrive in media containing a wide range of NaCl concentrations ranging from about 0.05 M to saturation (around 5.5 M). The algae contain no rigid polysaccharide cell wall and thus have been found to be able to rapidly change their volume and shape in response to changes in the extracellular hypo- or hyper-osmotic pressure. In osmotic adjustment, the osmoregulatory response of Dunaliella functions to maintain osmotic balance at high salinities by synthesis and varying the intracellular concentration of glycerol. In this review, we describe the osmotic response process of Dunaliella under salinity stress, including the changes of cell volume, intracellular ions concentration, intracellular glycerol concentration, and the expression of some salt-induced genes. Some specific proteins and enzymes can be induced by different salinities in osmotic response process. In addition, we introduce the exogenous expression of salt-related genes of Dunaliella salina in plants and microorganisms for the purpose of confirming the functions of related genes, proteins, and enzymes. The aim of this review is to emphasize the importance of the studies on the mechanisms of osmotic adjustments of Dunaliella in order to develop its unique osmotic characteristics. It is prospected that future research should pay attention to the specific signal transduction pathway and the mechanism of osmoregulation, and to improve the salt tolerance of higher plants by using salt-tolerant genes of Dunaliella.
杜氏藻属中的一些物种具有独特的能力，能够大量积累β-胡萝卜素，并能在含有约0.05 M至饱和（约5.5 M）的广泛NaCl浓度的培养基中生长。这些藻类没有坚硬的多糖细胞壁，因此已发现它们能够根据细胞外低渗或高渗压力的变化迅速改变其体积和形状。在渗透调节中，杜氏藻的渗透调节反应通过合成和改变细胞内甘油浓度来维持高盐度下的渗透平衡。在这篇综述中，我们描述了盐度胁迫下杜氏藻的渗透反应过程，包括细胞体积、细胞内离子浓度、细胞内甘油浓度的变化以及一些盐诱导基因的表达。在渗透反应过程中，不同盐度可诱导一些特定的蛋白质和酶。此外，为了证实相关基因、蛋白质和酶的功能，我们介绍了杜氏盐藻盐相关基因在植物和微生物中的外源表达。这篇综述的目的是强调研究杜氏藻渗透调节机制的重要性，以便开发其独特的渗透特性。展望未来的研究应关注具体的信号转导途径和渗透调节机制，并利用杜氏藻的耐盐基因提高高等植物的耐盐性。
