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 up-regulated. We discuss evidence for a framework that accounts for most of this syndrome. Disruption of chloroplast biogenesis prevents 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.

中文翻译：

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质体逆行信号：发育视角

叶绿体活动影响核基因表达，这种现象被称为逆行信号传导。当叶绿体发育受到破坏时，核基因表达的变化揭示了生物逆行信号。生物信号研究主要集中在光合作用相关核基因 (PhANG) 的抑制上，但这只是涉及多种过程的数千个基因表达改变的综合征的一个组成部分，其中许多基因上调。我们讨论了解释大部分这种综合症的框架的证据。叶绿体生物发生的破坏阻止了光合分化程序中离散步骤所需信号的产生，从而导致幼年状态的保留。结果，在光合分化过程中晚期起作用的 PhANG 和其他基因的表达不会被启动，而早期起作用的基因的表达被保留。幼年期的程度以及转录组反映了被破坏的过程：质体翻译的缺乏阻碍了早期的发育，而光合作用的破坏而不影响质体翻译则阻碍了后期的发育。我们讨论了这些和其他最近观察结果对调节光合分化的质体衍生信号的性质的影响，以及 GUN1（一种参与生物信号传导的神秘蛋白质）的作用。