RNA editing is a process which leads to post-transcriptional alteration of the nucleotide sequence of the corresponding mRNA molecule which may or may not lead to changes at the protein level. Apart from its role in providing variability at the transcript and protein levels, sometimes, such changes may lead to abnormal expression of the mitochondrial gene leading to a cytoplasmic male sterile phenotype. Here we report the editing status of 20 major mitochondrial transcripts in both male sterile (AKCMS11) and male fertile (AKPR303) pigeonpea genotypes. The validation of the predicted editing sites was done by mapping RNA-seq reads onto the amplified mitochondrial genes, and 165 and 159 editing sites were observed in bud tissues of the male sterile and fertile plant respectively. Among the resulting amino acid alterations, the most frequent one was the conversion of hydrophilic amino acids to hydrophobic. The alterations thus detected in our study indicates differential editing, but no major change in terms of the abnormal protein structure was detected. However, the above investigation provides an insight into the behaviour of pigeonpea mitochondrial genome in native and alloplasmic state and could hold clues in identification of editing factors and their role in adaptive evolution in pigeonpea.
Keywords: Cajanus cajan; Cajanus scarabaeoides; Cytoplasmic male sterility; Mitochondria; RNA editing.