Department of Microbiology and Cell Biology, Indian Institute of Science, Bengaluru 560012, India.
Institute of Molecular Biology, University of Oregon, Eugene, OR 97403, USA.
Plant Cell. 2024 Oct 3;36(10):3903-3913. doi: 10.1093/plcell/koae094.
Chloroplast activities influence nuclear gene expression, a phenomenon referred to as retrograde signaling. Biogenic retrograde signals have been revealed by changes in nuclear gene expression when chloroplast development is disrupted. Research on biogenic signaling has focused on repression of Photosynthesis-Associated Nuclear Genes (PhANGs), but this is just one component of a syndrome involving altered expression of thousands of genes involved in diverse processes, many of which are upregulated. We discuss evidence for a framework that accounts for most of this syndrome. Disruption of chloroplast biogenesis prevents the production of signals required to progress through discrete steps in the program of photosynthetic differentiation, causing retention of juvenile states. As a result, expression of PhANGs and other genes that act late during photosynthetic differentiation is not initiated, while expression of genes that act early is retained. The extent of juvenility, and thus the transcriptome, reflects the disrupted process: lack of plastid translation blocks development very early, whereas disruption of photosynthesis without compromising plastid translation blocks development at a later stage. We discuss implications of these and other recent observations for the nature of the plastid-derived signals that regulate photosynthetic differentiation and the role of GUN1, an enigmatic protein involved in biogenic signaling.
叶绿体活动影响核基因表达，这种现象被称为逆行信号。当叶绿体发育受到干扰时，核基因表达的变化揭示了生物逆行信号。生物信号的研究集中在抑制光合作用相关核基因（PhANGs）上，但这只是涉及数千个参与不同过程的基因表达改变的综合征的一个组成部分，其中许多基因被上调。我们讨论了一个可以解释这个综合征大部分内容的框架的证据。叶绿体生物发生的破坏阻止了在光合作用分化程序中通过离散步骤所必需的信号的产生，导致幼年状态的保留。结果，PhANGs 和其他在光合作用分化后期起作用的基因的表达不会被启动，而在早期起作用的基因的表达则被保留。幼态的程度，以及因此转录组，反映了被破坏的过程：缺乏质体翻译会使发育非常早期就受阻，而不影响质体翻译的光合作用的破坏会在后期阻止发育。我们讨论了这些和其他最近的观察结果对调节光合作用分化的质体衍生信号的性质以及参与生物信号的神秘蛋白 GUN1 的作用的影响。
