Rosenwasser Shilo, Rot Ilona, Sollner Evelyn, Meyer Andreas J, Smith Yoav, Leviatan Noam, Fluhr Robert, Friedman Haya
Department of Postharvest Science of Fresh Produce, Agricultural Research Organization, The Volcani Center, Bet Dagan 50250, Israel.
Plant Physiol. 2011 May;156(1):185-201. doi: 10.1104/pp.110.169797. Epub 2011 Mar 3.
Treatment of Arabidopsis (Arabidopsis thaliana) leaves by extended darkness generates a genetically activated senescence program that culminates in cell death. The transcriptome of leaves subjected to extended darkness was found to contain a variety of reactive oxygen species (ROS)-specific signatures. The levels of transcripts constituting the transcriptome footprints of chloroplasts and cytoplasm ROS stresses decreased in leaves, as early as the second day of darkness. In contrast, an increase was detected in transcripts associated with mitochondrial and peroxisomal ROS stresses. The sequential changes in the redox state of the organelles during darkness were examined by redox-sensitive green fluorescent protein probes (roGFP) that were targeted to specific organelles. In plastids, roGFP showed a decreased level of oxidation as early as the first day of darkness, followed by a gradual increase to starting levels. However, in mitochondria, the level of oxidation of roGFP rapidly increased as early as the first day of darkness, followed by an increase in the peroxisomal level of oxidation of roGFP on the second day. No changes in the probe oxidation were observed in the cytoplasm until the third day. The increase in mitochondrial roGFP degree of oxidation was abolished by sucrose treatment, implying that oxidation is caused by energy deprivation. The dynamic redox state visualized by roGFP probes and the analysis of microarray results are consistent with a scenario in which ROS stresses emanating from the mitochondria and peroxisomes occur early during darkness at a presymptomatic stage and jointly contribute to the senescence program.
拟南芥（Arabidopsis thaliana）叶片经长时间黑暗处理会引发一种基因激活的衰老程序，最终导致细胞死亡。研究发现，长时间黑暗处理的叶片转录组包含多种活性氧（ROS）特异性特征。早在黑暗处理的第二天，构成叶绿体和细胞质ROS应激转录组足迹的转录本水平就在叶片中下降。相反，与线粒体和过氧化物酶体ROS应激相关的转录本有所增加。通过靶向特定细胞器的氧化还原敏感绿色荧光蛋白探针（roGFP）检测了黑暗期间细胞器氧化还原状态的顺序变化。在质体中，roGFP早在黑暗处理的第一天就显示出氧化水平下降，随后逐渐增加至起始水平。然而，在线粒体中，roGFP的氧化水平早在黑暗处理的第一天就迅速增加，随后在第二天过氧化物酶体中roGFP的氧化水平也增加。直到第三天，细胞质中的探针氧化才出现变化。蔗糖处理消除了线粒体roGFP氧化程度的增加，这意味着氧化是由能量剥夺引起的。roGFP探针可视化的动态氧化还原状态以及微阵列结果分析与一种情况相符，即线粒体和过氧化物酶体产生的ROS应激在黑暗早期的症状前阶段就已出现，并共同促成衰老程序。
