Exposure of Arabidopsis thaliana to Cd or Cu excess leads to oxidative stress mediated alterations in MAPKinase transcript levels

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• 作者：Kelly Opdenakker ^{kelly.opdenakker@uhasselt.be} ; Tony Remans ^{tony.remans@uhasselt.be} ; Els Keunen ^{els.keunen@uhasselt.be} ; Jaco Vangronsveld ^{jaco.vangronsveld@uhasselt.be} ; Ann Cuypers ; ^{ann.cuypers@uhasselt.be}
• 关键词：Cadmium ; Copper ; Oxidative stress ; Signal transduction ; Arabidopsis thaliana ; MAPkinases
• 刊名：Environmental and Experimental Botany
• 出版年：2012
• 出版时间：November, 2012
• 年：2012
• 卷：83
• 期：Complete
• 页码：53-61
• 全文大小：552 K

文摘

Metals, like cadmium (Cd) and copper (Cu), have the ability to induce the production of reactive oxygen species (ROS) at the cellular level. It is widely known that these ROS can cause irreversible damage to cellular components, like DNA, proteins and lipids. On the other hand, ROS can also act as signaling molecules and in this way they play an essential role in many normal physiological processes, but also in defense responses against stress. ROS signaling in plants uses mitogen-activated protein kinase (MAPK) pathways leading to the transcriptional control of target genes involved in the scavenging or production of ROS. Here, oxidative signaling induced by exposure to excess Cd or Cu was investigated in relation to anti-oxidative defense responses to these metals. Three-week-old Arabidopsis thaliana plants were exposed to environmentally realistic concentrations of Cu and Cd and immediate responses were measured at the level of hydrogen peroxide (H₂O₂) content, lipid peroxidation and transcript levels of genes involved in ROS homeostasis and signaling. Our findings show immediate (after 2 h exposure) effects in the roots following Cu exposure, whereas effects in the leaves were generally more delayed. Effects of Cd exposure in leaves and roots were observed only after 24 h exposure. On one hand, exposure of roots to Cu leads via activation of NADPH oxidases and Fenton reactions to H₂O₂ production that can induce MAPK and oxylipin signaling to control the cellular redox status. On the other hand, conversion of H₂O₂ to the more damaging hydroxyl radical by Fenton and Haber-Weiss reactions can initiate lipid peroxidation leading to membrane damage. In roots exposed to elevated Cd concentrations only oxidative signaling was initiated, possibly via NADPH oxidase-mediated ROS production. In leaves, time-dependent activation of MAPK and oxylipin signaling was seen after exposure to both metals, Cu or Cd, independent of changes in H₂O₂ content.