Integrated role of ROS and Ca⁺² in blue light-induced chloroplast avoidance movement in leaves of Hydrilla verticillata (L.f.) Royle

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• 作者：Arkajo Majumdar ; Rup Kumar Kar
• 关键词：Blue light ; Calcium ; Chloroplast movements ; ROS ; Signal transduction
• 刊名：Protoplasma
• 出版年：2016
• 出版时间：November 2016
• 年：2016
• 卷：253
• 期：6
• 页码：1529-1539
• 全文大小：2,894 KB
• 刊物类别：Biomedical and Life Sciences
• 刊物主题：Life Sciences
  Cell Biology
  Plant Sciences
  Zoology
  
• 出版者：Springer Wien
• ISSN：1615-6102
• 卷排序：253

文摘

Directional chloroplast photorelocation is a major physio-biochemical mechanism that allows these organelles to realign themselves intracellularly in response to the intensity of the incident light as an adaptive response. Signaling processes involved in blue light (BL)-dependent chloroplast movements were investigated in Hydrilla verticillata (L.f.) Royle leaves. Treatments with antagonists of actin filaments [2,3,5-triiodobenzoic acid (TIBA)] and microtubules (oryzalin) revealed that actin filaments, but not microtubules, play a pivotal role in chloroplast movement. Involvement of reactive oxygen species (ROS) in controlling chloroplast avoidance movement has been demonstrated, as exogenous H₂O₂ not only accelerated chloroplast avoidance but also could induce chloroplast avoidance even in weak blue light (WBL). Further support came from experiments with different ROS scavengers, i.e., dimethylthiourea (DMTU), KI, and CuCl₂, which inhibited chloroplast avoidance, and from ROS localization using specific stains. Such avoidance was also partially inhibited by ZnCl₂, an inhibitor of NADPH oxidase (NOX) as well as 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), a photosynthetic electron transport chain (ETC) inhibitor at PS II. However, methyl viologen (MV), a PS I ETC inhibitor, rather accelerated avoidance response. Exogenous calcium (Ca+2) induced avoidance even in WBL while inhibited chloroplast accumulation partially. On the other hand, chloroplast movements (both accumulation and avoidance) were blocked by Ca+2 antagonists, La3+ (inhibitor of plasma membrane Ca+2 channel) and ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid (EGTA, Ca+2 chelator) while LiCl that affects Ca+2 release from endosomal compartments did not show any effect. A model on integrated role of ROS and Ca+2 (influx from apolastic space) in actin-mediated chloroplast avoidance has been proposed.