A grant has been awarded to Dr. Meerow of USDA Agricultural Research Service in Miami, Florida to complete studies on the evolutionary relationships of the large flowering plant family Amaryllidaceae using DNA sequences and morphological characters. The family, consisting almost entirely of showy-flowered plants that grow from bulbs, is highly valued in horticulture. Meerow is noted internationally as a leading specialist in the family. Previous work by him and co-workers using both chloroplast and nuclear DNA sequences has contributed to understanding the relationships of this family to other closely related groups such as the onion family (Alliaceae). That the family is a natural unit was confirmed, and geographically based groups of common ancestry were resolved. The earliest branch in the amaryllis family tree is found in Africa where the family likely originated. However, three chloroplast DNA sequence data sets failed to resolve the relationships between two remaining African groups (or "tribes" in botanical lexicon), a small tribe restricted to Australasia, and the Eurasian and American genera of the family, the latter two groups sharing common ancestry. Using a nuclear DNA sequence, Meerow and co-workers were able to present a highly resolved estimate of the relationships among the American genera which have resulted in a much more natural classification. The current work to be funded by NSF has two objectives: 1) complete a family-wide data matrix of nucleotide sequences of the ndhF chloroplast gene for all genera of the Amaryllidaceae, with the express purpose of resolving the relationships of the major lineages, and 2) use sequences of the internal transcribed spacer (ITS) of 18S-26S nuclear ribosomal DNA to resolve the Eurasian group of the family, as proved to be so successful for the American group. The Eurasian group includes the economically important genus Narcissus, one of the five most popular spring-flowering bulbs in the world. For the family-wide analysis, gene sequences will be combined with morphological data. Genomic DNA will be extracted from fresh or silica gel-dried leaf tissue of approximately 59 species of Amaryllidaceae representing all genera (chloroplast ndhF), and 20-25 species of the Eurasian group (nuclear ITS), using standard procedures. Target sequences will be amplified using the polymerase chain reaction PCR). Both strands of the target DNA sequences will be run on automated sequencers. DNA sequences will be aligned, and subjected to phylogenetic analysis and confidence testing using various computer programs. At the same time, analyses of the Amaryllidaceae using morphological and cytological characters will be completed. Comparative and combined analyses should elucidate a robust phylogeny upon which a final, accurate classification of the Amaryllidaceae can be based. Phylogenetic and taxonomic analyses of the Amaryllidaceae will improve documentation of biodiversity patterns in the tropics, facilitate study of biogeographic migrations and regions of endemism, guide selection of stocks for horticultural improvement, and identify clusters of related species and genera that may share biosynthetic capabilities, in a family well-known for producing novel alkaloids, some poisonous to humans, but others potentially of pharmaceutical interest. As the family is highly valued in horticulture, especially genera of the Eurasian group, there is more than passing interest among non-scientists in understanding the evolutionary relationships of the genera. In the course of conducting this research, undergraduate students recruited from local area universities will have the opportunity to become acquainted with techniques of molecular taxonomic analysis in Meerow's laboratory.
