Department of Plant and Microbial Biology, University of California, Berkeley, California 94720, USA.
Plant Physiol. 2012 Jan;158(1):190-9. doi: 10.1104/pp.111.186130. Epub 2011 Nov 9.
Recent studies suggest that intercellular transport via plasmodesmata (PD) is regulated by cellular redox state. Until now, this relationship has been unclear, as increased production of reactive oxygen species (ROS) has been associated with both increased and decreased intercellular transport via PD. Here, we show that silencing two genes that both increase transport via PD, INCREASED SIZE EXCLUSION LIMIT1 (ISE1) and ISE2, alters organelle redox state. Using redox-sensitive green fluorescent proteins targeted to the mitochondria or plastids, we show that, relative to wild-type leaves, plastids are more reduced in both ISE1- and ISE2-silenced leaves, whereas mitochondria are more oxidized in ISE1-silenced leaves. We further show that PD transport is positively regulated by ROS production in mitochondria following treatment with salicylhydroxamic acid but negatively regulated by an oxidative shift in both chloroplasts and mitochondria following treatment with paraquat. Thus, oxidative shifts in the mitochondrial redox state positively regulate intercellular transport in leaves, but oxidative shifts in the plastid redox state counteract this effect and negatively regulate intercellular transport. This proposed model reconciles previous contradictory evidence relating ROS production to PD transport and supports accumulating evidence that mitochondria and plastids are crucial regulators of PD function.
最近的研究表明，通过胞间连丝（PD）的细胞间运输受细胞氧化还原状态的调节。到目前为止，这种关系还不清楚，因为活性氧（ROS）的产生增加与 PD 介导的细胞间运输增加和减少都有关。在这里，我们表明，沉默两个都能增加 PD 运输的基因（ISE1 和 ISE2）会改变细胞器的氧化还原状态。我们使用靶向线粒体或质体的氧化还原敏感的绿色荧光蛋白，表明与野生型叶片相比，ISE1 和 ISE2 沉默叶片中的质体还原程度更高，而 ISE1 沉默叶片中的线粒体氧化程度更高。我们进一步表明，在用水杨基羟肟酸处理后，线粒体中 ROS 的产生正向调节 PD 运输，但在用百草枯处理后，叶绿体和线粒体中的氧化转变负向调节 PD 运输。因此，线粒体氧化还原状态的氧化转变正向调节叶片中的细胞间运输，但质体氧化还原状态的氧化转变抵消了这种效应并负向调节细胞间运输。该模型解释了先前关于 ROS 产生与 PD 运输的矛盾证据，并支持了越来越多的证据，即线粒体和质体是 PD 功能的关键调节剂。
