Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, S-90187 Umeå, Sweden.
Australian Research Council Centre of Excellence in Plant Energy Biology, School of Molecular Sciences, University of Western Australia, Crawley, Western Australia 6009, Australia.
Plant Physiol. 2018 Feb;176(2):1199-1214. doi: 10.1104/pp.17.00435. Epub 2017 Jun 16.
Chloroplasts develop from undifferentiated proplastids present in meristematic tissue. Thus, chloroplast biogenesis is closely connected to leaf development, which restricts our ability to study the process of chloroplast biogenesis per se. As a consequence, we know relatively little about the regulatory mechanisms behind the establishment of the photosynthetic reactions and how the activities of the two genomes involved are coordinated during chloroplast development. We developed a single cell-based experimental system from Arabidopsis () with high temporal resolution allowing for investigations of the transition from proplastids to functional chloroplasts. Using this unique cell line, we could show that the establishment of photosynthesis is dependent on a regulatory mechanism involving two distinct phases. The first phase is triggered by rapid light-induced changes in gene expression and the metabolome. The second phase is dependent on the activation of the chloroplast and generates massive changes in the nuclear gene expression required for the transition to photosynthetically functional chloroplasts. The second phase also is associated with a spatial transition of the chloroplasts from clusters around the nucleus to the final position at the cell cortex. Thus, the establishment of photosynthesis is a two-phase process with a clear checkpoint associated with the second regulatory phase allowing coordination of the activities of the nuclear and plastid genomes.
叶绿体由分生组织中存在的未分化前质体发育而来。因此，叶绿体的生物发生与叶片发育密切相关，这限制了我们对叶绿体生物发生本身过程的研究能力。结果，我们对光合作用反应建立背后的调控机制以及在叶绿体发育过程中如何协调两个相关基因组的活性了解甚少。我们从拟南芥（Arabidopsis）中开发了一个具有高时间分辨率的单细胞实验系统，允许对从前质体到功能叶绿体的转变进行研究。使用这种独特的细胞系，我们可以证明光合作用的建立依赖于一种涉及两个不同阶段的调控机制。第一阶段是由快速光诱导的基因表达和代谢组变化触发的。第二阶段依赖于叶绿体的激活，并产生大量的核基因表达变化，这对于向具有光合作用功能的叶绿体的转变是必需的。第二阶段还与叶绿体从核周围的簇到最终在细胞皮层的位置的空间转变有关。因此，光合作用的建立是一个具有明确检查点的两阶段过程，该检查点与第二调控阶段相关，允许核和质体基因组的活性协调。
