Tuteja Narendra
Plant Molecular Biology, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi, India.
Methods Enzymol. 2007;428:419-38. doi: 10.1016/S0076-6879(07)28024-3.
Among abiotic stresses, high salinity stress is the most severe environmental stress, which impairs crop production on at least 20% of irrigated land worldwide. In response to high salinity stress, various genes get upregulated, the products of which are involved either directly or indirectly in plant protection. Some of the genes encoding osmolytes, ion channels, receptors, components of calcium signaling, and some other regulatory signaling factors or enzymes are able to confer salinity-tolerant phenotypes when transferred to sensitive plants. Overall, the susceptibility or tolerance to high salinity stress in plants is a coordinated action of multiple stress responsive genes, which also cross talk with other components of stress signal transduction pathways. High salinity exerts its negative impact mainly by disrupting the ionic and osmotic equilibrium of the cell. In saline soils, high levels of sodium ions lead to plant growth inhibition and even death; therefore, mechanisms of salinity tolerance involve sequestration of Na(+) and Cl(-) in vacuoles of the cells, blocking of Na(+) entry into the cell, Na(+) exclusion from the transpiration stream, and some other mechanisms that help in salinity tolerance. Understanding these mechanisms of stress tolerance, along with a plethora of genes involved in the stress signaling network, is important to improve high salinity stress tolerance in crops plants. This chapter first describes the adverse effect of salinity stress and general pathway for the plant stress response, followed by roles of various ion pumps, calcium, SOS pathways, ABA, transcription factors, mitogen-activated protein kinases, glycine betaine, proline, reactive oxygen species, and DEAD-box helicases in salinity stress tolerance. The cross-tolerance between stresses is also mentioned.
在非生物胁迫中，高盐胁迫是最严重的环境胁迫，它影响着全球至少20%灌溉土地上的作物产量。作为对高盐胁迫的响应，各种基因被上调，其产物直接或间接参与植物保护。一些编码渗透调节物质、离子通道、受体、钙信号传导成分以及其他一些调节信号因子或酶的基因，当被转移到敏感植物中时能够赋予耐盐表型。总体而言，植物对高盐胁迫的易感性或耐受性是多个胁迫响应基因的协同作用，这些基因也与胁迫信号转导途径的其他成分相互作用。高盐主要通过破坏细胞的离子和渗透平衡来施加其负面影响。在盐渍土壤中，高浓度的钠离子会导致植物生长受抑制甚至死亡；因此，耐盐机制包括将Na⁺和Cl⁻隔离在细胞液泡中、阻止Na⁺进入细胞、将Na⁺从蒸腾流中排除以及其他一些有助于耐盐的机制。了解这些胁迫耐受机制以及胁迫信号网络中涉及的大量基因，对于提高作物对高盐胁迫的耐受性很重要。本章首先描述了盐胁迫的不利影响和植物胁迫响应的一般途径，随后介绍了各种离子泵、钙、SOS途径、脱落酸、转录因子、丝裂原活化蛋白激酶、甘氨酸甜菜碱、脯氨酸、活性氧和DEAD-box解旋酶在耐盐胁迫中的作用。还提到了胁迫之间的交叉耐受性。
