MORF2 is a key effector of plastidial retrograde signaling for stress response and plant morphogenesis beyond RNA editing
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ABSTRACT: Multiple Organellar RNA Editing Factor 2 (MORF2) was previously discovered to be involved in chloroplast RNA editing. However, the albino and unviable phenotype of the T-DNA insertion mutants, morf2-1 and morf2-2, seems to be inconsistent with many other viable chloroplast RNA editing mutants, suggesting that MORF2 has other biological functions beyond RNA editing.
Project description:Microarray analysis of two nonphotosynthetic nuclear mutants (mcd1-1, mcd1-2) that affect chloroplast RNA stability to identify affected organellar genes (chloroplast and mitochondrial). Further, the photosynthetic suppressor (mcd2-1) that suppresses mcd1-2 was included to determine which genes respond directly to the RNA stabilty phenotype and which respond to the nonphotosynthetic phenotype. Keywords: repeat sample
Project description:Microarray analysis of two nonphotosynthetic nuclear mutants (mcd1-1, mcd1-2) that affect chloroplast RNA stability to identify affected organellar genes (chloroplast and mitochondrial). Further, the photosynthetic suppressor (mcd2-1) that suppresses mcd1-2 was included to determine which genes respond directly to the RNA stabilty phenotype and which respond to the nonphotosynthetic phenotype.
Project description:We extended the investigation of nuclear transcript changes under drought to an overarching characterization of the post(transcriptome), including alternative splicing of nuclear transcripts, accumulation of organellar (chloroplast and mitochondrion) transcripts, editing and splicing of organellar transcripts, and furthermore, accumulation of transposable elements. To this end, long non-coding (lncRNA-Seq) instead of mRNA-Seq was applied, because the lncRNA-Seq workflow employs library preparation after ribosomal RNA depletion instead of library preparation of enriched mRNAs (mRNA-Seq).
Project description:Changes ins organellar gene expression trigger retrograde signalling. Prolyl-tRNA synthetase (PRORS1) is located in chloroplasts and mitochondria. Thus, prors1-2 mutants are impaired in chloroplast and mitochondrial gene expression. The effects of the prors1-2 mutation on the global transcriptome were investigated with microarray analyses.
Project description:Changes ins organellar gene expression trigger retrograde signalling. Prolyl-tRNA synthetase (PRORS1) is located in chloroplasts and mitochondria. Thus, prors1-2 mutants are impaired in chloroplast and mitochondrial gene expression. The effects of the prors1-2 mutation on the global transcriptome were investigated with microarray analyses. RNA was extracted from Col-0 (WT, 4-weeks-old) and prors1-2 (38-d-old) leaves of the same developmental stage
Project description:Heat stress inhibits photosynthesis efficiency, thereby suppressing plant growth and crop yield. However, the mechanism underlying this inhibition is not fully understood. Here, we report that the multiple organellar RNA-editing factor 8 (MORF8) forms condensates with solid-like properties in chloroplast upon heat stress. In vitro data show that the MORF8 condensation is intrinsically heat-dependent and primarily determined by its IDR (intrinsically disordered region). Purification and characterization of MORF8 condensates show that numerous editing factors including PPR proteins and MORFs are partitioned. We provide both genetic and biochemical evidence that MORF8 condensation inhibits chloroplast RNA editing. In agreement, we find that both heat stress and MORF8 condensation lead to reduced editing of RNAs encoding NADH dehydrogenase-like (NDH) complex and impaired NDH activity and photosynthesis efficiency. These findings uncover MORF8 as a putative chloroplastic thermosensor that mediates photosynthesis inhibition by heat and highlight the functional significance of solid material properties of biomolecular condensates.
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.
Project description:Study of the role of the FLV/DOT4 protein in post-transcriptional regulation of chloroplast gene expression. DOT4 is a pentatricopeptide repeat protein targeted to the chloroplast which regulates the editing of the rpoC1 transcript The editing level of rpoC1 varies from one tissue to the other and because the main macroscopic phenotype of the flv/dot4 mutant are white leaf margins. We compared the leaf border to the leaf center of wild-type Col0 plants but also the leaf borders of col0 and flv/dot4 knock out mutants by sequencing total RNA depleted from rRNA to get a global view of gene expression (including post-transcrional modifications) of the 3 plant genomes: nucleus, chloroplast and mitochondria. mRNA seq on wild-type Col and FLV mutants knock out.
Project description:This data analyzes gene expression patterns in Arabidopsis whitening mutants, wn1, with defects in chloroplast development. We found that wn1 was a T-DNA insertion line of Arabidopsis AtPTAC10/PAP3 (At3g48500) and exhibited a lethal, albino-like phenotype in the seedling stages. pTAC10 was known as a component of RNA polymerase complex called plastid-encoded RNA polymerase, PEP, in mature chloroplasts. Because wn1 mutants were lethal, we extracted RNA from cotyledons of 7-day-old seedlings from wn1 mutants and Col-0. RNA seq analysis was commissioned by NICEM in Seoul National University, Korea and transcriptome resequencing was confirmed in Macrogen, Korea. Through analysis, we compared gene expression patterns of wn1 mutant and Col-0 seedlings.
Project description:Canonical retrograde signalling comprises information transmission from organelles to the nucleus and in particular controls gene expression for organellar proteins. The need to re-assess this paradigm was suggested by discrepancies between de novo protein synthesis and transcript abundance in response to excess light. Here we uncover major components of a translation-dependent retrograde signalling pathway that first impacts translation and then transcription. The response realization depends on the kinases Mitogen-activated protein kinase 6 (MPK6) and Sucrose non-fermenting 1-related kinase (SnRK1) subunit, AKIN10. Global ribosome foot-printing revealed differential ribosome association of 951 transcripts within 10 min after transfer from low to high light. Despite predominant translational repression, 15 % of transcripts were increased in translation and enriched for chloroplast-localized photosynthetic proteins. About one third of these transcripts, including Stress associated proteins (SAP) 2 and 3, share regulatory motifs in their 5`-UTR that act as binding sites for glyceraldehyde-3-phosphate dehydrogenase (GAPC) and light responsive RNA binding proteins (RBPs). SAP2 and 3 are both translationally regulated and interact with the calcium sensor Calmodulin-like 49 (CML49), which promotes relocation to the nucleus inducing a translation-dependent nuclear stress response. Thus, translation-dependent retrograde signalling bifurcates to directly regulate a translational circuit of chloroplast proteins and simultaneously initiate a nuclear circuit synchronizing retrograde and anterograde response pathways, serving as a rapid mechanism for functional acclimation of the chloroplast.