In Arabidopsis thaliana distinct alleles encoding mitochondrial RNA PROCESSING FACTOR 4 support the generation of additional 5' termini of ccmB transcripts.

In plant mitochondria, the 5' ends of many transcripts are generated post-transcriptionally. We show that the pentatricopeptide repeat (PPR) protein RNA PROCESSING FACTOR 4 (RPF4) supports the generation of extra 5' ends of ccmB transcripts in Landsberg erecta (Ler) and a number of other Arabidopsis thaliana ecotypes. RPF4 was identified in Ler applying a forward genetic approach supported by complementation studies of ecotype Columbia (Col), which generates the Ler-type extra ccmB 5' termini only after the introduction of the RPF4 allele from Ler.

Maturation of 5' ends of plant mitochondrial RNAs.

The generation of mature RNAs, i.e. mRNAs, rRNAs or tRNAs, is a complex process in all genetic systems.

In Arabidopsis thaliana two co-adapted cyto-nuclear systems correlate with distinct ccmC transcript sizes.

Plant mitochondrial transcripts undergo maturation processes at both termini. Although frequently observed, the post-transcriptional formation of mature 5' ends is still poorly understood. We now analyzed the processing of transcripts derived from the mitochondrial ccmC gene, coding for a component of the cytochrome c maturation system.

P-class pentatricopeptide repeat proteins are required for efficient 5' end formation of plant mitochondrial transcripts.

It is well recognized that flowering plants maintain a particularly broad spectrum of factors to support gene expression in mitochondria. Many of these factors are pentatricopeptide repeat (PPR) proteins that participate in virtually all processes dealing with RNA. One of these processes is the post-transcriptional generation of mature 5' termini of RNA.

RNA Processing Factor 5 is required for efficient 5' cleavage at a processing site conserved in RNAs of three different mitochondrial genes in Arabidopsis thaliana.

The 5' ends of many mitochondrial transcripts are generated post-transcriptionally. Recently, we identified three RNA PROCESSING FACTORs required for 5' end maturation of different mitochondrial mRNAs in Arabidopsis thaliana. All of these factors are pentatricopeptide repeat proteins (PPRPs), highly similar to RESTORERs OF FERTILTY (RF), that rescue male fertility in cytoplasmic male-sterile lines from different species.

Mitochondrial transcript length polymorphisms are a widespread phenomenon in Arabidopsis thaliana.

Natural genetic variation affects development, physiology, biochemical properties as well as mitochondrial transcripts of the model species Arabidopsis thaliana (Arabidopsis). In a previous study, we identified mitochondrial transcript end polymorphisms in Arabidopsis accessions Columbia, C24 and Landsberg erecta. The polymorphic transcript species could either be assigned to differences in the mitochondrial DNA or to natural genetic variation in the nucleus.