School of Biological Sciences, University of Nebraska, Lincoln, NE, 68588, USA.
Plant Cell Environ. 2017 Sep;40(9):1704-1710. doi: 10.1111/pce.12967. Epub 2017 Jul 14.
Experiencing diverse and recurring biotic and abiotic stresses throughout life, plants have evolved mechanisms to respond, survive and, eventually, adapt to changing habitats. The initial response to drought involves a large number of genes that are involved also in response to other stresses. According to current models, this initial response is non-specific, becoming stress-specific only at later time points. The question, then, is whether non-specific activation of various stress-signalling systems leading to the expression of numerous stress-regulated genes is a false-alarm (panicky) response or whether it has biologically relevant consequences for the plant. Here, it is argued that the initial activation of genes associated other stresses reflects an important event during which stress-specific mechanisms are generated to prevent subsequent activation of non-drought signalling pathways. How plants discriminate between a first and a repeated dehydration stress and how repression of non-drought specific genes is achieved will be discussed on the example of jasmonic acid-associated Arabidopsis genes activated by a first, but not subsequent, dehydration stresses. Revealing how expression of various biotic/abiotic stress responding genes is prevented under recurring drought spells may be critical for our understanding of how plants respond to dynamically changing environments.
在整个生命周期中，植物经历着多种多样且反复出现的生物和非生物胁迫，因此进化出了一系列应对、存活并最终适应不断变化的栖息地的机制。植物对干旱的最初响应涉及到大量基因，这些基因也参与了对其他胁迫的响应。根据当前的模型，这种最初的响应是非特异性的，只有在稍后的时间点才会变得具有胁迫特异性。那么问题是，各种胁迫信号系统的非特异性激活导致众多胁迫调节基因的表达，是一种虚警（恐慌）反应，还是对植物具有生物学上的相关后果。在这里，有人认为，与其他胁迫相关的基因的最初激活反映了一个重要事件，在此期间，产生了胁迫特异性机制，以防止随后非干旱信号通路的激活。植物如何区分第一次和重复的脱水胁迫，以及如何实现非干旱特异性基因的抑制，将以拟南芥中茉莉酸相关基因为例进行讨论，这些基因在第一次但不是随后的脱水胁迫中被激活。揭示在反复出现的干旱期如何防止各种生物/非生物胁迫应答基因的表达，可能对我们理解植物如何应对动态变化的环境至关重要。
