M. Reith et J. Munholland, A HIGH-RESOLUTION GENE MAP OF THE CHLOROPLAST GENOME OF THE RED ALGA PORPHYRA-PURPUREA, The Plant cell, 5(4), 1993, pp. 465-475
Extensive DNA sequencing of the chloroplast genome of the red alga Por
phyra purpurea has resulted in the detection of more than 125 genes. F
ifty-eight (approximately 46%) of these genes are not found on the chl
oroplast genomes of land plants. These include genes encoding 17 photo
synthetic proteins, three tRNAs, and nine ribosomal proteins. In addit
ion, nine genes encoding proteins related to biosynthetic functions, s
ix genes encoding proteins involved in gene expression, and at least f
ive genes encoding miscellaneous proteins are among those not known to
be located on land plant chloroplast genomes. The increased coding ca
pacity of the P. purpurea chloroplast genome, along with other charact
eristics such as the absence of introns and the conservation of ancest
ral operons, demonstrate the primitive nature of the P. purpurea chlor
oplast genome. In addition, evidence for a monophyletic origin of chlo
roplasts is suggested by the identification of two groups of genes tha
t are clustered in chloroplast genomes but not in cyanobacteria.