Arabidopsis Mitochondrial Transcription Termination Factor mTERF2 Promotes Splicing of Group IIB Introns

Members of the mitochondrial transcription termination factor (mTERF) family regulate gene expression in chloroplasts and/or mitochondria at different steps. Here, we investigated the molecular function of chloroplast-localized mTERF2 in Arabidopsis thaliana. Loss-of-function mterf2 mutants are embryo lethal. Thus, artificial microRNA-mediated mterf2 knockdown plants were generated. In amiR-mterf2 mutants, plant development is perturbed and chlorophyll content reduced. A defect in photosynthesis is accompanied by reduced levels of photosystem subunits, although corresponding messenger RNA levels are unaffected. RNA immunoprecipitation followed by RNA sequencing (RIP-Seq) experiments combined with whole-genome RNA-Seq, RNA gel-blot and quantitative RT-PCR analyses revealed the requirement of mTERF2 for splicing of the group IIB introns of ycf3 (intron 1) and rps12. Examination of differential gene expression in the Arabdidopsis thaliana artificial micro RNA generated mterf2 knock-down mutant compared to wild type in three replicates