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.
2012-03-02 | GSE24517 | GEO
Project description:RADseq in Dactylorhiza and related genera
| PRJNA489792 | ENA
Project description:Repeat dynamics in sibling allotetraploid Dactylorhiza
Project description:Plastids communicate with the nucleus by means of retrograde plastid signals. The far-red (FR) light insensitive Arabidopsis mutant laf6 disrupted in a plastid-localised ABC-like protein (atABC1) accumulates the plastid signal protoporphyrin IX (proto IX) and has attenuated nuclear gene expression (Moller et al.2001 Genes Dev. 15:90-103). Our data suggests that proto IX accumulation results in hypocotyl elongation in response to FR light and we have demonstrated that by inhibiting the plastid localised protoporphyrinogen IX oxidase (PPO) using flumioxazin wild-type plants phenocopy laf6 by accumulating proto IX with a concomitant loss of hypocotyl growth inhibition in a dose-dependent manner. It is at present unclear what effect increased proto IX has on nuclear gene expression and how this is integrated with photomorphogenic responses such as hypocotyl elongation.
Project description:Upon exposure to light, plant cells quickly acquire photosynthetic competence by converting pale etioplasts into green chloroplasts. This developmental transition involves the de novo biogenesis of the thylakoid system, and requires reprogramming of metabolism and gene expression. Etioplast-to-chloroplast differentiation involves massive changes in plastid ultrastructure, but how these changes are connected to specific changes in physiology, metabolism and expression of the plastid and nuclear genomes is poorly understood. Here a new experimental system in the dicotyledonous model plant tobacco (Nicotiana tabacum) that allows us to study the leaf de-etiolation process at the systems level. We have determined the accumulation kinetics of photosynthetic complexes, pigments, lipids and soluble metabolites, and recorded the dynamic changes in plastid ultrastructure and in the nuclear and plastid transcriptomes. Our data describe the greening process at high temporal resolution, resolve distinct genetic and metabolic phases during de-etiolation, and reveal numerous candidate genes that may be involved in light-induced chloroplast development and thylakoid biogenesis.
Project description:Retrograde signaling from the chloroplast to the nucleus is necessary to regulate the chloroplast proteome during development and fluctuating environmental conditions. Although the specific chloroplast process(es) that must occur and the nature of the signal(s) that exits the chloroplast are not well understood, previous studies using drug inhibitors of chloroplast biogenesis have revealed that normal chloroplast development is required to express Photosynthesis Associated Nuclear Genes (PhANGs). In an attempt to determine which specific steps in chloroplast development are involved in retrograde signaling, we analyzed Arabidopsis mutants defective in the six genes encoding sigma factor (Sig) proteins that are utilized by the plastid-encoded RNA polymerase to transcribe specific sets of plastid genes. Here, we demonstrate that both Sig2 and Sig6 have partially redundant roles in not only plastid transcription, but also tetrapyrrole synthesis and retrograde signaling to control PhANG expression. Normal PhANG expression can be partly restored in the sig2 mutant by increasing heme synthesis. Furthermore, there is a genetic interaction between Sig and GUN (genomes uncoupled) genes to generate chloroplast-retrograde signals. These results demonstrate that defective plastid transcription is the source of at least two retrograde signals to the nucleus; one involving tetrapyrrole synthesis and the other involving the accumulation of an unknown plastid transcript. We also propose that the study of sig mutants (with defects in the expression of specific plastid genes) provides a new genetic system, which avoids the use of harsh inhibitors and their potential side effects, to monitor developmental retrograde signaling and to elucidate its mechanisms.