TANK, DAVID C.* AND TAO SANG. Department of Botany and Plant Pathology, Michigan State University, East Lansing, MI 48824. - The glycerol-3-phosphate acyltransferase gene in Paeonia (Paeoniaceae): molecular evolution and phylogenetic utility.
The nuclear encoded glycerol-3-phosphate acyltransferase gene (GPAT)
has been found to be single copy in a number of angiosperm families.
In this study we investigated the phylogenetic utility of the GPAT
gene in determining the interspecific relationships of the angiosperm
genus Paeonia. An approximately 2.3 kb fragment of the GPAT
gene was amplified, cloned, and sequenced from all diploid and
selected tetraploid species of Paeonia. The GPAT gene may
exist as a single copy in some species of Paeonia, but
constitutes a small gene family in others. Two distinct genomic
clones of P. anomala containing the GPAT gene have been
characterized and suggest that the gene underwent an ancient
duplication followed by the formation of a pseudogene in one copy.
Blast sequence similarity analysis suggests that the GPAT pseudogene
may contain a large retrotransposon-like insertion that could have
triggered the pseudogene formation. The rate of evolution of the GPAT
gene was determined to be greater than that of the nuclear ITS region
in Paeonia, demonstrating the potential of the GPAT gene to be
used in resolving low-level taxonomic relationships of angiosperms.
When compared to existing gene phylogenies, such as the cpDNA
matK gene, nuclear ITS region and the alcohol dehydrogenase
genes, the GPAT gene phylogeny yielded additional insights into the
relationships within Paeonia.
Key words: nuclear gene GPAT, Paeonia, Paeoniaceae