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:Light triggers chloroplast differentiation whereby the etioplast transforms into a photosynthesizing chloroplast and the thylakoid rapidly emerges. However, the sequence of events during chloroplast differentiation remains poorly understood. Here we used whole-seedling proteome data to quantify changes in protein abundances during the course of de-etiolation within the first four days of light exposure. This data complements quantitative lipid and (ultra)structural data described in Pipitone et al. (doi: https://doi.org/10.1101/2020.08.30.274043).
Project description:Chloroplast, the energy organelle unique to plants and green algae, performs a wide range of functions including photosynthesis and biosynthesis of metabolites. However, as the most important tuber crop worldwide, the potato (Solanum tuberosum) chloroplast proteome has not been explored. Here, we use Percoll density gradient centrifugation to isolate intact chloroplasts from leaves of potato cultivar E3 and establish a reference proteome map of potato chloroplast by bottom-up proteomics. A total of 1834 non-redundant proteins, including 51 proteins encoded by the chloroplast genome, were identified in the chloroplast proteome. Extensive sequence-based localization prediction revealed over 62% of proteins to be chloroplast resident by at least one algorithm. A total of 16 proteins were selected for evaluating the prediction result by transient fluorescence assay and confirmed that 14 of them were distributed on distinct internal compartments of the chloroplast. In addition, 136 phosphorylation sites were identified in 61 proteins encoded by chloroplast proteome. Furthermore, by a comparative analysis between chloroplast and previously reported amyloplast proteomes, we reconstruct the starch metabolic pathways in the two different types of plastids. Altogether, our results establish a comprehensive proteome map with post-translationally modified sites of potato chloroplast, which would provide the theoretical principle for the research of photosynthesis pathway and starch metabolism.
Project description:Deep sequencing provided evidence that a novel subset of small RNAs were derived from the chloroplast genome of Chinese cabbage (Brassica rapa) and Arabidopsis (Ler). The chloroplast small RNAs (csRNAs) include those derived from mRNA, rRNA, tRNA and intergenic RNA. The rRNA-derived csRNA were preferentially located at the 3â-ends of the rRNAs, while the tRNA-derived csRNAs were mainly located at 5â-termini of the tRNAs. After heat treatment, the abundance of csRNAs decreased in chinese cabbage seedlings, except those of 24 nt in length. The novel heat-responsive csRNAs and their locations in the chloroplast were verified by Northern blotting. The regulation of some csRNAs to the putative target genes were identified by real-time PCR. Our results indicated that high temperature regulated the production of some csRNAs, which may have potential roles in transcriptional or post-transcriptional regulation, and affected putative target genes expression in chloroplast.
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.