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United States Department of Agriculture

Agricultural Research Service


Location: Subtropical Horticulture Research

2013 Annual Report

1a. Objectives (from AD-416):
1. Conserving tropical/subtropical ornamental crop genetic resourses and associated information important for the evaluation and utilization of that material. 2. Development and application of new or improved horticultural evaluation procedures and genetic marker-based approaches for genetic diversity assessment of the preceding genetic resourses. 3. Genetic improvement efforts directed to developing new, superior tropical/ subtropical ornamental germplasm. 4. Transfer of technology in the form of tropical/subtropical ormamental crop genetic resourses, associated information, and new, superior tropical/subtropical ornamental germplasm to researchers and breeders worldwide. 5. Evaluate containerized subtropical/tropical ornamental germplasm for its growth responses to different container media components. Where feasible, estimate for this germplasm the heritabilities and other patterns of genetic variation for adaptation/tolerance to the different container media components.

1b. Approach (from AD-416):
Collect new accessions of subtropical/tropical ornamental plants that have commerical potential in the U.S. Evaluate newly collected accessions and existing material, primarily flowering trees and shrubs already on site, using phenotypic characters and molecular makers. Organize the information such that it can be used as descriptors for inclusion in the GRIN system. Utilize the molecular and phenotypical analysis to breed improved germplasm in support of the ornamental industry. Communicate and coordinate subtropical/tropical ornamental horticultural research with local and regional industry, universites, and foreign germplasm effort in Florida, Puerto Rico, and Hawaii.

3. Progress Report:
All population of Zamia from Bahamas, Cayman Islands and Florida have been genotyped with 30 microsatellite loci. The only Zamia sample collections remaining to be made are from Cuba and collaborators are travelling there in July 2013. Sequencing of a subset of each population with 10 single copy genes has been completed for the Bahamas and Florida. ARS plant patent committee has approved patent for five amaryllis hybrids and patent applications are being prepared. We have begun an experiment to determine the best concentration and exposure duration of oryzalin for effective chromosome doubling in amaryllis. Sequences of five single copy genes were used in phylogenetic analysis of the entire order Cycadales. Preliminary data show that forms of nitrogen including ammonia (NH4NO3 or (NH4)2SO4) resulted in the best growth of Zamia pumila. Nitrate-N as the sole nitrogen source and organic nitrogen improved growth over plants receiving no nitrogen. Coralloid root development was poor in all treatments. Seed from Zamia floridana were collected and a second study is planned to confirm these results.

4. Accomplishments
1. A stable tree of life for the cycads. DNA sequences of five single copy nuclear genes were obtained for 20 cycad species representing all ten genera of the order Cycadales. These were analyzed with parsimony, maximum likelihood (ML), and three Bayesian methods of gene tree/species tree reconciliation, using Cycas as outgroup. A calibrated date estimation was developed with Bayesian methods, and biogeographic analysis was also conducted. Concatenated parsimony, ML, and three species tree inference methods resolve exactly the same tree topology with high support at most nodes. Dioon and Bowenia are the first and second branches of Cycadales after Cycas, respectively, followed by an encephalartoid clade (Macrozamia-Lepidozamia-Encephalartos), which is sister to a zamioid clade, of which Ceratozamia is the first branch, and in which Stangeria is sister to Microcycas and Zamia.

Review Publications
Meerow, A.W. 2012. Chapter II. Taxonomy and Phylogeny. Book Chapter. (2):17-55.

Calonje, M., Meerow, A.W., Knowles, L., Knowles, D., Griffith, P., Nakamura, K., Francisco-Ortega, J. 2013. Cycad biodiversity in the Bahama Archipelago and conservation genetics of the Critically Endangered Zamia lucayana (Zamiaceae). Oryx, The International Journal of Conservation. Oryx 47:190-198.

Meerow, A.W., Francisco-Ortega, J., Ayala Silva, T., Stevenson, D.W., Nakamura, K. 2012. Population genetics of Zamia in Puerto Rico, a preliminary study with ten SSR loci . Memoirs of the New York Botanical Garden. Memoirs of the New York Botanical Garden 106 : 204 – 223.

Meerow, A.W., Francisco-Ortega, J., Calonje, M., Ayala Silva, T., Griffith, P., Stevenson, D., Nakamura, K. 2012. The coontie’s new clothes: asymmetric genetic diversification within Zamia (Cycadales: Zamiaceae) on Puerto Rico, and an hypothesis of multiple introductions. American Journal of Botany. 99:1828-1839.

Ronsted, N., Symonds, M.R., Birkholm, T., Christensen, S., Meerow, A.W., Molander, M., Molgaard, P., Petersen, G., Rasmussen, N., Van Staden, J., Stafford, G.I., Jager, A.K. 2012. Can phylogeny predict chemical diversity and potential medicinal activity of plants? A case study of Amaryllidaceae. BMC Evolutionary Biology. 1471-2148/12/182.

Waters, M.T., Tiley, A.M., Kramer, E.M., Meerow, A.W., Langdale, J.A., Scotland, R.A. 2013. The corona of the daffodil Narcissus bulbocodium is distinct from the orthodox floral whorls.. Plant Journal. doi: 10.1111/tpj.12150.

Last Modified: 06/25/2017
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