SANG, TAO. Department of Botany & Plant Pathology, Michigan State University, East Lansing, MI 48824. - Utility of low-copy nuclear genes in plant phylogenetics.
Low-copy nuclear genes in plants are a rice source of phylogenetic
information. They hold a great potential to improve the robustness of
phylogenetic reconstructions at all taxonomical levels, especially
where universal markers such as cpDNA and nrDNA are unable to generate
a strong phylogenetic hypothesis. Low-copy nuclear genes, however,
remain underused in plant phylogenetic studies due to practical and
theoretical complications in unraveling evolutionary dynamics of a
nuclear gene family. The lack of the universal markers or universal
PCR primers of low-copy nuclear genes has also hampered their
phylogenetic utility. It has recently become clear that low-copy
nuclear genes are particularly helpful in resolving close
interspecific relationships and in reconstructing allopolyploidization
in plants. Gene markers that are widely, if not universal, useful have
begun to emerge. Although utilizing low-copy nuclear genes usually
requires extra lab work such as designing PCR primers, PCR-cloning,
and/or Southern blotting, rapid accumulation of gene sequences in the
databases and advances in cloning techniques have continued to make
such studies less labor-intensive. The growing number of theoretical
studies devoted to the gene tree and species tree problem began to
build a solid foundation for reconstructing complex plant phylogenies
based on multiple gene trees. It is also increasingly realized that
fast evolving introns of the low-copy nuclear genes will provide much
needed phylogenetic information around the species boundary, and allow
us to address fundamental questions concerning processes of plant
speciation.
Key words: low-copy nuclear genes, phylogeny