Sequence Homology between Chloroplast DNAs from Several Higher Plants

An estimate has been made of the amount of sequence homology present in the chloroplast DNA (ctDNA) of several higher plants by the technique of DNA-DNA hybridization. Approximately 85% of tomato, 60% of spinach, 45% of kale, and 15% of barley ctDNA sequences were found to hybridize with tobacco ctDNA under conditions in which maximum hybridization in homologous reactions reached 85%. All heteroduplexes contained significant amounts of sequence mismatch as indicated by a 3 to 9 C decrease in melting temperature as compared to homoduplex.