In this article we will discuss about the structure of rice mitochondrial genome.
Rice mitochondrial genome is made up of 492 kb nucleotides. The complexity of rice mitochondrial genome is due to the presence of chloroplast sequences. Hybridization analysis using clone banks of chloroplast DNA (ctDNA) and mtDNA from rice (Oryza sativa) confirmed the presence of chloroplast sequence in mtDNA of rice.
There are 16 chloroplast fragments in rice mtDNA ranging from 32 bp to about 6.8 kb in length. Thus, results show that about 6% (22 kb) of rice mtDNA is made up of chloroplast sequence. The mitochondrial genome of rice contains rearranged cluster of chloroplast genes, namely, rpl2 and yrpl23-rcL-atpB-atp E-trnM- trnV.
The genes for ribosomal proteins S3 (rps3) and L16 (rp116) in rice mtDNA have been documented. One of the palindromic repeated sequences (PRS) was located in the intron of rps3 in rice mtDNA, but not in maize mtDNA.
Analysis of transferred sequences of ctDNA in mtDNA of rice was evidenced in that at least three repeated sequences about 60 bp in length are present in plant. It was also found that rice mtDNA contained at least 10 copies of the small repeated sequence (Fig. 5.3).