Project description:In this study, we have characterized a putative chloroplast ribosome assembly factor. To elucidate transcriptional responses caused by decreased chloroplast function, we have measured the transcriptome of wild-type and knock-down seedlings.
Project description:The transition of chloroplast function from biogenesis to degeneration upon leaf senescence is critical for a plant’s fitness, as nutrient relocation from leaves to reproductive organs is achieved through this process. The optimal timing of transition should be regulated by tight coordination between chloroplast and nucleus, but the underlying mechanisms remain elusive. Here, we describe the regulatory mechanism of this transition. Chloroplast-Related LONG NONCODING RNA 1 (CHLORELLA1) is highly co-expressed with genes coding for chloroplast functionality during leaf development. Leaves of chlorella exhibit precocious senescence symptoms and a decline in the expression of chloroplast-associated genes, indicating that CHLORELLA1 plays a role in maintaining chloroplast function. Mechanistically, nucleus-encoded CHLORELLA1 transcripts are translocated into the chloroplast and contribute to the assembly of the plastid-encoded RNA polymerase (PEP) complex. At aged leaves, decreased expression of CHLORELLA1 attenuates PEP complex assembly and transcription of photosynthesis genes, possibly triggering leaf senescence. Moreover, CHLORELLA1 is directly activated by GLK1/2, master regulators of chloroplast maintenance. Our study unravels a new layer of the regulation via chloroplast-targeted lncRNA as an anterograde signal in timely decision of leaf senescence.
Project description:The coordination of chloroplast and nuclear genome status are critical for plant cell function, but the mechanism remain largely unclear. In this study, we report that Arabidopsis thaliana CHLOROPLAST AND NUCLEUS DUAL-LOCALIZED PROTEIN 1 (CND1) maintains genome stability in both the chloroplast and the nucleus.
Project description:Chloroplast biogenesis represents a crucial step in seedling development, and is essential for the transition to autotrophic growth in plants. This light-controlled process relies on the transcription of nuclear and plastid genomes that drives the effective assembly and regulation of the photosynthetic machinery. Here we reveal a novel regulation level for this process by showing the involvement of chromatin remodelling in the coordination of nuclear and plastid gene expression for proper chloroplast biogenesis and function. The two Arabidopsis homologs of the yeast EPL1 proteins, core components of the NuA4 histone acetyl-transferase complex, are essential for the correct assembly and performance of chloroplasts. EPL1 proteins are necessary for the coordinated expression of nuclear genes encoding most of the components of chloroplast transcriptional machinery, specifically promoting H4K5Ac deposition in these loci. These data unveil a key participation of epigenetic regulatory mechanisms in the coordinated expression of the nuclear and plastid genomes.
Project description:We found that thylakoid-anchored protein PBF8 is a key regulator for Photosystem I (PSI) biogenesis. To explore the role of PBF8 in regulating chloroplast gene expression, we performed the RNA-seq to compare the the transcript levels of chloroplast-encoded genes between wild type (Col-0) and pbf8 mutants. To this end, we isolated the total RNA form 12-day-old wild type and pbf8 seedlings grown on the MS medium under long-day conditions (14 h light, 10 h dark) at 22 ºC and with a light intensity of 80 µmol m-2 s-1. The rRNAs were deleted using the Ribo-Zero Kit (Epicentre). The resulting rRNA-depleted RNA was used for preparing the sequencing library with NEBNext Single Cell/Low input library Prep Kit. The libraries were pooled and sequenced on an Illumina Nova 6000 system with 150-bp pair-end reads. Finally, our results show that the transcript accumulation for chloroplast-encoded PSI subunit and assembly factor genes between the wild type (Col-0) and pbf8 samples, suggesting PBF8 may not affect the transcript levels of chloroplast-encoded PSI subunits and assembly factors in chloroplasts.
Project description:The coordination of chloroplast and nuclear genome status are critical for plant cell function, but the mechanism remain largely unclear. In this study, we report that Arabidopsis thaliana CHLOROPLAST AND NUCLEUS DUAL-LOCALIZED PROTEIN 1 (CND1) maintains genome stability in both the chloroplast and the nucleus.