Project description:We report that phosphatidylglycerol (PG) biosynthesis in plastid is required for plastid gene expression mediated by plastid-encoded RNA polymerase and light-induced expression of nuclear-encoded photosynthesis-associated genes. A transcription factor GOLDEN-LIKE1 was also found to be involved in the downregulation of nuclear photosynthesis genes in responce to PG deficiency.
Project description:Shortly after the release of singlet oxygen (1O2), drastic changes in nuclear gene expression occur in the conditional flu mutant of Arabidopsis that reveal a rapid transfer of signals from the plastid to the nucleus. In contrast to retrograde control of nuclear gene expression by plastid signals described earlier, the primary effect of 1O2 generation in the flu mutant is not the control of chloroplast biogenesis but the activation of a broad range of signaling pathways known to be involved in biotic and abiotic stress responses. This activity of a plastid-derived signal suggests a new function of the chloroplast, namely that of a sensor of environmental changes that activates a broad range of stress responses. Inactivation of the plastid protein EXECUTER1 attenuates the extent of 1O2-induced up-regulation of nuclear gene expression, but it does not fully eliminate these changes. A second related nuclear-encoded protein, dubbed EXECUTER2, has been identified that is also implicated with the signaling of 1O2-dependent nuclear gene expression changes. Like EXECUTER1, EXECUTER2 is confined to the plastid. Inactivation of both EXECUTER proteins in the ex1/ex2/flu triple mutant is sufficient to suppress the up-regulation of almost all 1O2-responsive genes. Retrograde control of 1O2-responsive genes requires the concerted action of both EXECUTER proteins within the plastid compartment. Keywords: biotic and abiotic stress response, nuclear gene expression, plastid-derived signal, Col-0 ecotype, continuous light and then dark-incubated plants
Project description:Plastids emit signals that broadly affect cellular processes. Based on previous genetic analyses, we propose that plastid signaling regulates the downstream components of a light signaling network and that these interactions coordinate chloroplast biogenesis with both the light environment and development by regulating gene expression. We tested these ideas by analyzing light-regulated and plastid-regulated transcriptomes. We found that the plastid is a major regulator of light signaling, attenuating the expression of more than half of all light-regulated genes in our dataset and changing the nature of light regulation for a smaller fraction of these light-regulated genes. Our analyses provide evidence that light and plastid signaling are interactive processes and are consistent with these interactions serving as major drivers of chloroplast biogenesis and function.
Project description:Plastids communicate with the nucleus through retrograde signaling pathways that coordinate nuclear and plastid gene expression to support plant development and environmental adaptation. However, how plastid regulatory factors are dynamically controlled to modulate these signals remains largely unknown. Here we identify a proteostasis mechanism that regulates plastid retrograde signaling through the ubiquitin–26S proteasome system. We show that the nuclear-encoded plastid RNA-editing factor MULTIPLE ORGANELLAR RNA EDITING FACTOR 2 (MORF2) is targeted for degradation by a Skp1–Cullin1–F-box (SCF) ubiquitin ligase assembled with the MORF2-INTERACTING F-BOX (MIF) protein. MIF physically associates with MORF2 and promotes its ubiquitylation and proteasome-dependent turnover. Genetic and physiological analyses reveal that this pathway balances early plant development. MIF overexpression suppresses seedling growth and disrupts chloroplast structure and function, whereas mif null mutants or MORF2 overaccumulation retard seed germination and reduce photosynthetic efficiency. Transcriptomic profiling and RNA-editing analyses further demonstrate that MIF-dependent MORF2 turnover modulates plastid RNA editing and retrograde signaling pathways. Together, our results uncover a previously unrecognized cytoplasmic regulatory layer that links ubiquitin-mediated proteostasis to plastid RNA editing and retrograde signaling. This mechanism enables plants to coordinate seed germination and chloroplast development during early seedling establishment.
2026-04-16 | GSE325043 | GEO
Project description:RADseq in Dactylorhiza and related genera