Institute of Botany, Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Dúbravská cesta 9, 84523, Bratislava, Slovak Republic.
Plant Mol Biol. 2022 Jan;108(1-2):145-155. doi: 10.1007/s11103-021-01233-w. Epub 2021 Dec 20.
Already a short-term Cd treatment induces changes in gene expression in barley root tips via IAA and ROS signaling during mild and severe Cd stress, respectively. Even a short, 30 min, Cd treatment of roots induced a considerable alteration in gene expression in the barley root tips within an hour after the treatments. The very early activation of MYB1 transcription factor expression is partially regulated by auxin signaling in mildly stressed seedlings. An increase in allene oxide cyclase and NADPH oxidase expression was a distinguishing feature of root tips response to mild Cd stress and their expression is activated via IAA signaling. Meanwhile, early changes in the level of dehydrin transcripts were detected in moderately and severely stressed root tips, and their induction is related to altered ROS homeostasis in cells. The early activation of glutathione peroxidase expression by mild Cd stress indicates the involvement of IAA in the signaling process. In contrast, early ascorbate peroxidase expression was induced only with Cd treatment causing severe stress and ROS play central roles in its induction. The expression of cysteine protease was activated similarly in both mildly and severely Cd-stressed roots; consequently, both increased IAA and ROS levels take part in the regulation of cysteine protease expression. The Cd-evoked accumulation of BAX Inhibitor-1 mRNA was characteristic for moderately and severely stressed roots. Whereas decreased IAA level did not affect its expression, rotenone-mediated ROS depletion markedly reduced the Cd-induced expression of BAX Inhibitor-1. An early increase of alternative oxidase levels in the root tip cells indicated that the reduction of mitochondrial superoxide generation is an important component of barley root response to severe Cd stress.
已有研究表明，在轻度和重度镉胁迫下，生长素（IAA）和活性氧（ROS）信号分别诱导短期镉处理后大麦根尖基因表达的变化。甚至在根系受到 30 分钟的镉处理后，在处理后一个小时内，大麦根尖的基因表达就发生了相当大的改变。在轻度胁迫的幼苗中，MYB1 转录因子表达的早期激活部分受到生长素信号的调节。在轻度 Cd 胁迫下，丙二烯氧化物环化酶和 NADPH 氧化酶表达的增加是根尖响应的一个显著特征，其表达通过 IAA 信号激活。同时，在中度和重度胁迫的根尖中检测到脱水素转录物水平的早期变化，其诱导与细胞中 ROS 稳态的改变有关。轻度 Cd 胁迫下谷胱甘肽过氧化物酶表达的早期激活表明 IAA 参与了信号转导过程。相反，只有在 Cd 处理导致严重胁迫时，早期的抗坏血酸过氧化物酶表达才被诱导，ROS 在其诱导中起核心作用。半胱氨酸蛋白酶的表达在轻度和重度 Cd 胁迫的根系中均被激活；因此，增加的 IAA 和 ROS 水平均参与了半胱氨酸蛋白酶表达的调节。在中度和重度胁迫的根系中，Cd 诱导的 BAX Inhibitor-1 mRNA 积累是特征性的。虽然降低 IAA 水平不会影响其表达，但鱼藤酮介导的 ROS 耗竭显著降低了 Cd 诱导的 BAX Inhibitor-1 表达。根尖细胞中交替氧化酶水平的早期增加表明，减少线粒体超氧化物的产生是大麦根系应对重度 Cd 胁迫的一个重要组成部分。
