KIM, SANGTAE1*, DOUGLAS E. SOLTIS1, PAMELA S. SOLTIS2, and YOUNGBAE SUH3. 1Department of Botany, University of Florida; 2Florida Museum of Natural History, University of Florida; 3Natural Products Research Institute, Seoul National University. - An ndhF sequence from a Miocene Magnolia.
Since the first report of an rbcL sequence of fossil
Magnolia from the Clarkia fossil beds (17-20 MYBP), the
validity of "fossil DNA" from this site has been questioned.
However, an rbcL sequence from a fossil Taxodium was
reported later, and here we report a partial ndhF sequence of a
fossil Magnolia from this fossil site. Use of closely spaced
primers, developed during a molecular phylogenetic study of
Magnoliaceae, and a two step PCR method produced sufficient PCR
product for sequencing from a very small amount of fragmented fossil
template. With this approach 1504 base pairs of ndhF sequences
were determined from a fossil leaf of M. latahensis. Parsimony
analysis of this sequence and previously reported ndhF genes in
Magnoliaceae placed M. latahensis at the base of the Theorhodon
clade with zero branch length. The ndhF sequence of M.
latahensis was identical to those of extant M. grandiflora,
M. schediana, M. guatemalensis, and M.
tamaulipana. This result is reasonable considering: 1) The
morphology of M. latahensis is very similar to that of M.
grandiflora although the other species placed with M.
latahensis in the Theorhodon clade possess very different
morphologies. 2) A recent molecular phylogenetic study of the family
showed that the maximum sequence divergences of ndhF in extant
Magnoliaceae is very low (1.05% in subfamily Magnolioideae) compared
with other angiosperm families. 3) The possibility of contamination is
extremely low because DNA of M. latahensis was extracted,
amplified, and sequenced in the USA, and other Magnoliaceae were
studied in Korea. We re-analyzed the previously reported rbcL
sequence of M. latahensis with sequences for all major lineages
of extant Magnoliaceae. The M. latahensis rbcL sequence
is the sister group of the two subfamilies of Magnoliaceae in this
analysis, rather than a close relative of M. grandiflora as
predicted by morphology and the results of the ndhF analysis.
Key words: fossil DNA, Magnolia latahensis, Magnoliaceae, Miocene fossil, ndhF, rbcL