Phylogenetic and Taxonomic Status Analyses of the Abaso Section from Multiple Nuclear Genes and Plastid Fragments Reveal New Insights into the North America Origin of Populus (Salicaceae)

作   者：刘霞，王兆山，邵文豪，叶占洋，张建国
期刊名称：Frontiers in Plant Science
影响因子：4.298
卷 期 号：
页     码：
关键词：plant evolution, phylogenetic, chloroplast DNA, single-copy nuclear, taxonomic status, Populus mexicana
论文摘要：
Although, the Abaso section is widely accepted as an independent section, the
taxonomic status of Populus mexicana (section Abaso) has not yet been resolved
due to the limited availability markers and/or the lack of P. mexicana specimens in
previous studies. Thirty-one poplar species that represent six sections of the Populus
genus were sampled, and 23 single-copy nuclear DNA and 34 chloroplast fragments
were sequenced. The present study obtained two updated phylogenies of Populus.
We found that monophyly of the genus Populus is strongly supported by nuclear and
plastid gene, which is consistent with previous studies. P. mexicana, diverged first in the
nuclear DNA tree, which occupied the basal position, implying that the section Abaso
may be the most ancestral lineage in extant populous species. Given that the short
branches and low statistical support for the divergence of sections Abaso and Turanga,
this observation probably indicated that a rapid radiation evolution following the early
split of the genus Populus. In the plastid tree, P. mexicana clustered with modern-day
species of section Tacamahaca in the plastid tree. Based on cytoplasmic and singlecopy
nuclear marker sequences, we hypothesized that chloroplast capture resulted in
the inconsistent position of P. mexicana between the phylogenetic trees. Given the first
unequivocal records of poplar fossils from the Eocene with similar leaf morphology to
the extant P. mexicana and the phylogenetic positions of P. mexicana in our study, we
support the hypothesis that the Populus genus originated in North America, which will
provide new insights to the development of the origin of Populus species.