Discovery of Chloroplast DNA, Genomes and Genes

It was discovered in the 1840s that plastids divide and in the early 1900s that they inherit some traits in a non-Mendelian (maternal) manner. It was established in 1962 that plastids contain DNA. With the advent of the techniques of molecular biology, restriction endonuclease recognition sites and genes for rRNAs were mapped on chloroplast chromosomes starting before 1976. The first chloroplast gene for a protein was located in 1977 and the sequence of this gene was reported in 1980. The complete sequences of two plastid chromosomes were reported in 1986. As of the end of 1996 nine plastid genomes had been completely sequenced. Although the functions of the protein products of many chloroplast genes remain to be determined, it is clear that each of these genomes is different from all the others. The knowledge of chloroplast genes and genomes gained to date has greatly expanded our understanding of photosynthetic processes in several ways and thrown new light on the biology of plastids as well as on their origin and the evolution of nuclear and plastid genomes.