The Mutation Of A Mitochondrial Pentatricopeptide Repeat Protein Causes Arabidopsis Thaliana Yellow And Lethal

Pentatricopeptide repeat(PPR)proteins,particularly abundant in chloroplasts and mitochondria of terrestrial plants,represent a large number of sequence-specific RNA binding proteins that are involved in diverse functional aspects of organelle RNA metabolisms.The Arabidopsis genome encodes 500 proteins containing the PPR motif.The PPR proteins are classified into two groups,termed as P and P Long-Short(PLS)classes.Typically,the PLS subclass proteins are mainly involved in the RNA editing of mitochondrial and chloroplast transcripts,whereas most of the analyzed P subclass proteins have been mainly implicated in RNA metabolism,such RNA stabilization and processing,splicing and translation.PPR proteins provide the specificity for these reactions.They recognize RNA sequences in a partially predictable fashion via key amino acids at the fifth and last position in each PPR motif that bind to individual ribonucleotides.Mutations of PPR genes often result in embryogenesis and altered seedling developmental defect phenotypes,but only a limited number of ppr mutants have been characterized in detail.In this study,we obtained an Arabidopsis yellow and lethal,namely yl.The Homozygous mutant plants inhibited yellow and seedling lethal phenotype,can be partially rescued by the addition of sucrose to the growth medium.The yl mutant was studied in detail by means of reverse genetics and molecular biology.The main results and conclusions of this study are as follows:(1)Using the method TADEA-PCR,we successfully cloning the junction sites of T-DNA transformants,found a deletion mutation present in AT3G53690 and AT3G53700.(2)Genetic analysis and Complement test indicated that mutation within the AT3G53700 was responsible for the yl phenotype.(3)AT3G53700 encodes a mitochondria-localized PPR protein with 17 PPR motifs,MEE40(MATERNAL EFFECT EMBRYO ARREST 40),belonging to the PLS subfamily.BLASTP search showed that the homologs of the MEE40 protein were present in various plant species.Alignment analysis results indicated that MEE40 was conserved in the evolutionary process.(4)DEGs were analyzed basically through transcriptome sequencing between WT and yl plants.MEE40 probably play several roles in mitochondria gene expression,further studies are needed to identify the molecular mechanisms.