OsPPR6, a pentatricopeptide repeat protein involved in editing and splicing chloroplast RNA, is required for chloroplast biogenesis in rice
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OsPPR6, a pentatricopeptide repeat protein involved in editing and splicing chloroplast RNA, is required for chloroplast biogenesis in rice.
The chloroplast has its own genetic material and genetic system, but it is also regulated by nuclear-encoded genes. However, little is known about nuclear-plastid regulatory mechanisms underlying early chloroplast biogenesis in rice. In this study, we isolated and characterized a mutant, osppr6, that showed early chloroplast developmental defects leading to albino leaves and seedling death. We found that the osppr6 mutant failed to form thylakoid membranes. Using map-based cloning and complementation tests, we determined that OsPPR6 encoded a new Pentatricopeptide Repeat (PPR) protein localized in plastids. In the osppr6 mutants, mRNA levels of plastidic genes transcribed by the plastid-encoded RNA polymerase decreased, while those of genes transcribed by the nuclear-encoded RNA polymerase increased. Western blot analyses validated these expression results. We further investigated plastidic RNA editing and splicing in the osppr6 mutants and found that the ndhB transcript was mis-edited and the ycf3 transcript was mis-spliced. Therefore, we demonstrate that OsPPR6, a PPR protein, regulates early chloroplast biogenesis and participates in editing of ndhB and splicing of ycf3 transcripts in rice.
KeywordsRice PPR Chloroplast biogenesis RNA editing RNA splicing
Transmission electron microscope
Nuclear-encoded plastid RNA polymerase
Plastid-encoded RNA polymerase
Pentatricopeptide repeat protein
Multiple organellar RNA editing factors
Receptor interacting protein
Ethyl methyl sulfonate
Open reading frame
Simple sequence repeats
Green fluorescent protein
Chloroplast transit peptide
Reactive oxygen species
Stain coomassie brilliant blue stain
The National Key Research and Development Project (2016YFD0101107, 2016YFD0100700), and National Key Technology Support Program project (2015BAD01B02-7), China supported this study. CW was supported by the “Shuangchuang”, Project (2012), and “Innovation Team Core Member” (2013) 140, Jiangsu Province, China. The funding agencies had no role in the study design, data collection and analysis, decision to publish, or manuscript preparation.
CW conceived the experiments and wrote the manuscript; JW supervised this research; J.T. performed the experiments and wrote the manuscript; WZ and FK provided the plant materials; KW, GC, JS, YT, TW, JY, HA and TW participated in the experiments; WT revised manuscript; the all authors read and approved the final manuscript.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing interests.
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