Dataset Information

A chloroplast-targeted pentatricopeptide repeat protein PPR287 is crucial for chloroplast function and Arabidopsis development.

ABSTRACT:

Background

Even though the roles of pentatricopeptide repeat (PPR) proteins are essential in plant organelles, the function of many chloroplast-targeted PPR proteins remains unknown. Here, we characterized the function of a chloroplast-localized PPR protein (At3g59040), which is classified as the 287th PPR protein among the 450 PPR proteins in Arabidopsis ( http://ppr.plantenergy.uwa.edu.au ).

Results

The homozygous ppr287 mutant with the T-DNA inserted into the last exon displayed pale-green and yellowish phenotypes. The microRNA-mediated knockdown mutants were generated to further confirm the developmental defect phenotypes of ppr287 mutants. All mutants had yellowish leaves, shorter roots and height, and less seed yield, indicating that PPR287 is crucial for normal Arabidopsis growth and development. The photosynthetic activity and chlorophyll content of ppr287 mutants were markedly reduced, and the chloroplast structures of the mutants were abnormal. The levels of chloroplast rRNAs were decreased in ppr287 mutants.

Conclusions

These results suggest that PPR287 plays an essential role in chloroplast biogenesis and function, which is crucial for the normal growth and development of Arabidopsis.

SUBMITTER: Lee K

PROVIDER: S-EPMC6555926 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundThe chloroplast is the organelle responsible for photosynthesis in higher plants. The generation of functional chloroplasts depends on the precise coordination of gene expression in the nucleus and chloroplasts and is essential for the development of plants. However, little is known about nuclear-plastid regulatory mechanisms at the early stage of chloroplast generation in rice.ResultsIn this study, we identified a rice (Oryza sativa) mutant that exhibited albino and seedling-lethal phenotypes and named it ssa1(seedling stage albino1). Transmission electron microscopy (TEM) analysis indicated that the chloroplasts of ssa1 did not have organized thylakoid lamellae and that the chloroplast structure was destroyed. Genetic analysis revealed that the albino phenotypes of ssa1 were controlled by a pair of recessive nuclear genes. Map-based cloning experiments found that SSA1 encoded a pentapeptide repeat (PPR) protein that was allelic to OSOTP51,which was previously reported to participate in Photosystem I (PSI) assembly. The albino phenotype was reversed to the wild type (WT) phenotype when the normal SSA1 sequence was expressed in ssa1 under the drive of the actin promoter. Knockout experiments further created mutants ssa1-2/1-9, which had a phenotype similar to that of ssa1. SSA1 consisted of 7 pentatricopeptide repeat domains and two C-terminal LAGLIDADG tandem sequence motifs and was located in the chloroplast. GUS staining and qRT-PCR analysis showed that SSA1 was mainly expressed in young leaves and stems. In the ssa1 mutants, plastid genes transcribed by plastid-encoded RNA polymerase decreased, while those transcribed by nuclear-encoded RNA polymerase increased at the mRNA level. Loss-of-function SSA1 destroys RNA editing of ndhB-737 and intron splicing of atpF and ycf3-2 in the plastid genome. Yeast two-hybrid and BiFC assays revealed that SSA1 physically interacted with two new RNA editing partners, OsMORF8 and OsTRXz, which have potential functions in RNA editing and chloroplast biogenesis.ConclusionsRice SSA1 encodes a pentatricopeptide repeat protein, which is targeted to the chloroplast. SSA1 regulates early chloroplast development and plays a critical role in RNA editing and intron splicing in rice. These data will facilitate efforts to further elucidate the molecular mechanism of chloroplast biogenesis.