Dynamism of plastid gene expression by intracellular communication

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This research purpose is to define the network of gene expression by communication between organelles and nuclear genomes within a plant cell. The novel findings obtained are as follows.1.We constructed a plastid DNA chip for microarray analysis of plastid genes from the moss, Physcomitrella patens.2.We reported phylogenetic analyses using 51 genes from the entire plastid genome sequences of 20 representative plant species. This indicated that extant bryophytes (mosses, liverworts, and hornworts) form a monophyletic group with high statistical confidence and that extant bryophytes are likely sisters to extant vascular plants. We propose bryophyte monophyly as the current best hypothesis.3.We developed plastid transformation technique for the moss, Physcomitrella patens and constructed stable plastid trnR-CCG knockout moss transformants. The trnR-CCG knockout transformants indicated that the P.patens trnR-CCG gene is not essential for plastid function.4.We identified a nuclear gene, PpR … More poA, encoding the alpha subunit of plastid-encoded plastid RNA polymerase (PEP). We generated and characterized PpRpoA knockout mosses. Primer extension, northern blot, run-on transcription assay and in vitro transcription assays first demonstrated that both PEP and NEP(nuclear-encoded plastid RNA polymerase) exist in the moss and recognize the common promoters of photosynthesis genes and non-photosynthesis genes.5.We identified three PpSig genes encoding plastid sigma factor. Among the three PpSig genes, only PpSig5 was clearly controlled by the circadian clock and/or by blue light signaling in the moss P.patens.6.An extensive survey of the Physcomitrella expressed sequence tag(EST) databases revealed 36 ESTs encoding pentatricopeptide repeat(PPR) motif-containing proteins. We further characterized five full-length cDNAs encoding plastid-localized PPR proteins, PPR513-10 and PPR566-6 were expressed differentially in protonemata grown under different light-dark conditions, suggesting they have distinctive functions in chloroplasts. This is the first report and analysis of genes encoding PPR proteins in bryophytes. Less