Je. Stabile et al., COLINEARITY OF CHLOROPLAST GENOMES IN DIVERGENT ECOTYPES OF THE MARINE DIATOM SKELETONEMA-COSTATUM (BACILLARIOPHYTA), Journal of phycology, 31(5), 1995, pp. 795-800
The chloroplast genomes of three isolates of the marine diatom Skeleto
nema costatum (Grev.) Cleve were mapped and found to be 131 +/- 2 kb w
ith inverted repeats (IRs) of approximately 20 kb. In contrast to high
er plants, the psbA gene mapped to the IR, and rbcS mapped to the same
fragment as the rbcL gene in the large single-copy region. The maps o
f the three isolates were colinear and revealed as many as 20 site mut
ations out of a total of 47 sites. The number of site mutations among
isolates was consistent with previous data on their genetic diversity
and physiology. Comparisons of gene order among our maps and those of
three other diatom species showed that closely related genera retained
similar gene orders bur that more distantly related taxa exhibited ex
tensive rearrangements. We conclude that simple restriction fragment a
nalysis of chloroplast DNA is useful in, comparative studies of diatom
populations and species but that other analytical methods are more ap
propriate for phylogenetic studies at higher levels.