Beck Erwin H, Fettig Sebastian, Knake Claudia, Hartig Katja, Bhattarai Tribikram
Department of Plant Physiology, University of Bayreuth, D 95440 Bayreuth, Germany.
J Biosci. 2007 Apr;32(3):501-10. doi: 10.1007/s12038-007-0049-5.
Different environmental stresses to a plant may result in similar responses at the cellular and molecular level. This is due to the fact that the impacts of the stressors trigger similar strains and downstream signal transduction chains. A good example for an unspecific response is the reaction to stressors which induce water deficiency e.g.drought, salinity and cold, especially frost. The stabilizing effect of liquid water on the membrane bilayer can be supported by compatible solutes and special proteins. At the metabolic level, osmotic adjustment by synthesis of low-molecular osmolytes (carbohydrates, betains, proline) can counteract cellular dehydration and turgor loss. Taking the example of Pinus sylvestris, changes at the level of membrane composition, and concomitantly of photosynthetic capacity during frost hardening is shown. Additionally the effect of photoperiod as measured via the phytochrome system and the effect of subfreezing temperatures on the incidence of frost hardening is discussed. Extremely hydrophilic proteins such as dehydrins are common products protecting not only the biomembranes in ripening seeds (late embryogenesis abundant proteins)but accumulate also in the shoots and roots during cold adaptation, especially in drought tolerant plants. Dehydrins are characterized by conserved amino acid motifs, called the K-,Y-or S-segments. Accumulation of dehydrins can be induced not only by drought, but also by cold,salinity,treatment with abscisic acid and methyl jasmonate. Positive effects of the overexpression of a wild chickpea (Cicer pinnatifidum) dehydrin in tobacco plants on the dehydration tolerance is shown. The presentation discusses the perception of cold and drought,the subsequent signal transduction and expression of genes and their products. Differences and similarities between the plant responses to both stressors are also discussed.
对植物施加不同的环境胁迫可能会在细胞和分子水平上导致相似的反应。这是因为胁迫源的影响会触发相似的应激和下游信号转导链。一个非特异性反应的典型例子是植物对导致缺水的胁迫源的反应，例如干旱、盐度和寒冷，尤其是霜冻。液态水对膜双层的稳定作用可以通过相容性溶质和特殊蛋白质来维持。在代谢水平上，通过合成低分子渗透剂（碳水化合物、甜菜碱、脯氨酸）进行渗透调节可以抵消细胞脱水和膨压丧失。以欧洲赤松为例，展示了在抗冻硬化过程中膜组成水平以及光合能力的变化。此外，还讨论了通过光敏色素系统测量的光周期效应以及亚冰点温度对抗冻硬化发生率的影响。极具亲水性的蛋白质，如脱水蛋白，不仅是保护成熟种子生物膜的常见产物（晚期胚胎发生丰富蛋白），而且在冷适应过程中也会在茎和根中积累，尤其是在耐旱植物中。脱水蛋白的特征是具有保守的氨基酸基序，称为K、Y或S片段。脱水蛋白的积累不仅可以由干旱诱导，还可以由寒冷、盐度、脱落酸和茉莉酸甲酯处理诱导。研究表明，野生鹰嘴豆脱水蛋白在烟草植物中的过表达对耐旱性有积极影响。本报告讨论了对寒冷和干旱的感知、随后的信号转导以及基因及其产物的表达。还讨论了植物对这两种胁迫源反应的差异和相似之处。
