Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad, India.
Graduate School of Environmental and Life Science, Okayama University, Okayama, Japan.
Adv Exp Med Biol. 2018;1081:215-232. doi: 10.1007/978-981-13-1244-1_12.
Drought is one of the abiotic stresses which impairs the plant growth/development and restricts the yield of many crops throughout the world. Stomatal closure is a common adaptation response of plants to the onset of drought condition. Stomata are microscopic pores on the leaf epidermis, which regulate the transpiration/CO uptake by leaves. Stomatal guard cells can sense various abiotic and biotic stress stimuli from the internal and external environment and respond quickly to initiate closure under unfavorable conditions. Stomata also limit the entry of pathogens into leaves, restricting their invasion. Drought is accompanied by the production and/or mobilization of the phytohormone, abscisic acid (ABA), which is well-known for its ability to induce stomatal closure. Apart from the ABA, various other factors that accumulate during drought and affect the stomatal function are plant hormones (auxins, MJ, ethylene, brassinosteroids, and cytokinins), microbial elicitors (salicylic acid, harpin, Flg 22, and chitosan), and polyamines . The role of various signaling components/secondary messengers during stomatal opening or closure has been a matter of intense investigation. Reactive oxygen species (ROS) , nitric oxide (NO) , cytosolic pH, and calcium are some of the well-documented signaling components during stomatal closure. The interrelationship and interactions of these signaling components such as ROS, NO, cytosolic pH, and free Ca are quite complex and need further detailed examination.Low temperatures can have deleterious effects on plants. However, plants evolved protection mechanisms to overcome the impact of this stress. Cold temperature inhibits stomatal opening and causes stomatal closure. Cold-acclimated plants often exhibit marked changes in their lipid composition, particularly of the membranes. Cold stress often leads to the accumulation of ABA, besides osmolytes such as glycine betaine and proline. The role of signaling components such as ROS, NO, and Ca during cold acclimation is yet to be established, though the effects of cold stress on plant growth and development are studied extensively. The information on the mitigation processes is quite limited. We have attempted to describe consequences of drought and cold stress in plants, emphasizing stomatal closure. Several of these factors trigger signaling components in roots, shoots, and atmosphere, all leading to stomatal closure. A scheme is presented to show the possible signaling events and their convergence and divergence of action during stomatal closure. The possible directions for future research are discussed.
干旱是一种非生物胁迫，它会损害植物的生长/发育，并限制世界各地许多作物的产量。气孔关闭是植物对干旱条件的一种常见适应反应。气孔是叶片表皮上的微小孔隙，它调节叶片的蒸腾/CO 吸收。气孔保卫细胞可以感知来自内部和外部环境的各种非生物和生物胁迫刺激，并在不利条件下迅速响应启动关闭。气孔还限制病原体进入叶片，限制它们的入侵。干旱伴随着植物激素脱落酸（ABA）的产生和/或动员，ABA 以诱导气孔关闭而闻名。除了 ABA 之外，在干旱期间积累并影响气孔功能的各种其他因素是植物激素（生长素、茉莉酸甲酯、乙烯、油菜素内酯和细胞分裂素）、微生物诱导剂（水杨酸、harpin、Flg22 和壳聚糖）和多胺。气孔开放或关闭过程中各种信号成分/第二信使的作用一直是深入研究的主题。活性氧（ROS）、一氧化氮（NO）、细胞质 pH 值和钙是气孔关闭过程中一些有充分文献记载的信号成分。这些信号成分（如 ROS、NO、细胞质 pH 值和游离 Ca）之间的相互关系和相互作用非常复杂，需要进一步详细检查。低温对植物可能有有害影响。然而，植物进化出了保护机制来克服这种压力的影响。低温抑制气孔开放并导致气孔关闭。经过低温驯化的植物通常会表现出其脂质组成的明显变化，特别是膜的脂质组成。除了渗透物如甘氨酸甜菜碱和脯氨酸外，低温胁迫通常会导致 ABA 的积累。ROS、NO 和 Ca 等信号成分在低温驯化过程中的作用尚未确定，尽管低温胁迫对植物生长和发育的影响已被广泛研究。关于缓解过程的信息非常有限。我们试图描述干旱和冷胁迫对植物的影响，强调气孔关闭。其中一些因素会在根部、茎部和大气中触发信号成分，所有这些都导致气孔关闭。提出了一个方案来显示气孔关闭过程中可能的信号事件及其作用的收敛和发散。讨论了未来研究的可能方向。
