Re-sequencing of mitochondrial genes in a standard rice cultivar Nipponbare.

Background: Genomic sequence of a rice cultivar Nipponbare has been often used as a reference sequence since a whole-genomic sequence was first determined in 2005 by the International Rice Genome Sequencing Project. As for mitochondrial genomic sequence of Nipponbare, two groups have deposited their sequences into DDBJ/EMBL/GenBank under the accession numbers BA000029 and DQ167400. However, there are 19 discrepancies in the nucleotide sequences of 7 genes between BA000029 and DQ167400.

Rice MPR25 encodes a pentatricopeptide repeat protein and is essential for RNA editing of nad5 transcripts in mitochondria.

Pentatricopeptide repeat (PPR) proteins are involved in the modification of organelle transcripts. In this study, we investigated the molecular function in rice of the mitochondrial PPR-encoding gene MITOCHONDRIAL PPR25 (MPR25), which belongs to the E subgroup of the PPR family. A Tos17 knockout mutant of MPR25 exhibited growth retardation and pale-green leaves with reduced chlorophyll content during the early stages of plant development.

Transcriptome map of plant mitochondria reveals islands of unexpected transcribed regions.

Background: Plant mitochondria contain a relatively large amount of genetic information, suggesting that their functional regulation may not be as straightforward as that of metazoans. We used a genomic tiling array to draw a transcriptomic atlas of Oryza sativa japonica (rice) mitochondria, which was predicted to be approximately 490-kb long.

Results: Whereas statistical analysis verified the transcription of all previously known functional genes such as the ones related to oxidative phosphorylation, a similar extent of RNA expression was frequently observed in the inter-genic regions where none of the previously annotated genes are located.