8. ORGANELLE GENOME AND THEIR APPLICATION by P. SAVITHA AND R. USHA KUMARI

Abstract

Plastid and mitochondria are essential organelles in plant cells. Chloroplasts conduct photosynthesis in the presence of sunlight and mitochondria indirectly supply energy within plant cells; together they form the powerhouses of the cell. Both chloroplasts and mitochondria possess their own genomes. The chloroplast (cp) genome and mitochondrial (mt) genomes are often used for the study of plant evolution (Zhang et al., 2011). From the information of all sequenced cp genomes, most of them range from 120 to 160 kb in length and have GC contents of 30 to 40 per cent. Mt genomes of seed plants are unusually large and vary in size at least in an order of magnitude. Much of these variations occur within a single family. Seed plant mitochondrial genomes are characteristic for their very low mutation rate, frequent uptake of foreign DNA by intracellular and horizontal gene transfer, and dynamic structure (Turmel et al., 2003). In the past several years, we have witnessed a dramatic increase in the number of complete organellar genomes, especially those of plants. Until now, there are 206 complete cp genomes and 47 mt genomes having been deposited in Gen Bank Organelle Genome Resoures (Tongwu Zhang et al., 2012).