Abstract
We successfully transformed respiratory deficient mitochondria of Chlamydomonas reinhardtii with DNA-constructs containing compensating genes that restored the deficiency. PCR and sequencing analysis showed that homologous recombination occurred between the mitochondrial genome and the artificial DNA-constructs, and the frequency was roughly proportional to the length of sequence homology. Through this investigation, we found that respiratory deficient strains of C. reinhardtii can be divided into two groups: strains that are constantly transformable and those that could not be transformed in our experiments. All of the transformed mitochondria have deletions (0.7 to 1.5-kb) extending from the left terminus to somewhere in the cob gene of their linear 15.8-kb mitochondrial genome. In comparison, mitochondria of all the non-transformable strains have both of their genome termini in intact. This led us to speculate that mitochondria lacking their left genome terminus have unstable genomes and might have higher potential for recombination.
