The editing sites in the transcripts of mitochondrial atp6 gene of maize sterile lines and maintainer line

Using maize (Zea mays L.) cytoplasmic male-sterile lines T Huang Zao Si, C Huang Zao Si, S Huang Zao Si and maintainer line N Huang Zao Si as the plant materials, editing sites in the conservative area of mitochondrial atp6 gene transcripts of the 4 experimental materials' tassels, of which microspores had developed to uni-nucleate stage, were analyzed. The results showed that DNA sequences of the T, C and S male-sterile cytoplasms were completely unanimous, while being compared with the N-cytoplasm, all the sequences were similar except for the 27th and 28th nucleotides. However, the cDNA sequences of each cytoplasm were not always the same. By comparing DNA and cDNA sequences, we found that within the conservative area of atp6 gene transcripts there were 19, 22, 20 and 19 editing sites in the N, T, C and S cytoplasms, respectively. The 4 cytoplasms also shared 18 sites. The majority of the editings occurred at the 1st or the 2nd position of codons, which might alter the amino acid type. Most the shared editings were fully editing, and the 1st and the 19th sites were partially edited in nearly all cytoplasms, except for the 19th sites editing in the N-cytoplasm. The specific editings in each cytoplasm occurred in the form of partially editing. Thus the editing of atp6 gene in maize was not only sequence specific but also affected by cytoplasmic background. Furthermore, plant RNA editing was inclined to improve the predicted protein's hydrophobicity and enhance the conservation among species.