Location: Subtropical Horticulture Research2013 Annual Report
1a. Objectives (from AD-416):
1. Characterize and evaluate priority NPGS woody landscape and herbaceous subtropical/tropical plant germplasm for key traits, such as their taxonomic identity, genetic variability, and ornamental merit, thereby enhancing the utility of these genetic resources for research and breeding. 1a. Phylogeography and conservation genetics of the Caribbean Zamia clade: an integrated systematic approach with SSRs and single copy nuclear genes. 1b. Development of single copy nuclear genes and the plastid gene ycf1 as phylogenetic markers in cycads, palms and amaryllids. 2. Identify the specific biochemical compounds responsible for floral fragrance and corolla color and determine their genetic basis for amaryllis and/or other selected members of the Amaryllidaceae. 2a. Identify the biochemical composition of floral fragrance in Hippeastrum brasilianum. 2b. Develop an in silico subtraction cDNA library for identifying genes for floral fragrance in Hippeastrum from floral transciptome data. 2c. Identify pigments involved with flower color in species of the genus Griffinia and Hippeastrum expressing purple coloration. 2d. Elucidate the genetic control of anthocyanin pigmentation in Hippeastrum (amaryllis) and genus Griffinia. 3. Develop superior new hybrid varieties and seedling selections of selected woody and herbaceous subtropical/tropical plants. 3a. Select, breed, and/or release new cultivars of the subtropical/ tropical shrub Portlandia, and trees Lagerstroemia specicosa and Handrosanthus impetiginosus. 3b. Tetraploidize selected diploid Hippeastrum hybrids, and continue selection and evaluation of Hippeastrum hybrid progeny. 4. Determine the effects of different fertilizer regimes on selected subtropical/tropical bulb crops, and the effects of different light regimes on selected species of ornamental palms. 4a. Determine the effect of N source on the growth of Hippeastrum bulbs. 4b. Determine the optimum light levels for production of ornamental palms during early growth and development. 4c. Determine the effect of N source and application rate on cyanobacterial colonization of cycad roots.
1b. Approach (from AD-416):
There are four broad objectives for the project. Objective 1 involves the development of genetic marker-based approaches for genetic diversity and systematic assessment of subtropical/tropical ornamentals, resulting in new classifications and reference information for taxonomic identification. Under this objective, microsatellite DNA, candidate gene, and DNA sequence approaches will be applied to diverse tropical ornamental germplasm, including cycads, palms, and Amaryllidaceae. Objective 2 will identify specific biochemical compounds associated with floral color and fragrance in selected members of the Amaryllidaceae and elucidate the genetic bases for these phenotypic characters. Objective 3 will conduct genetic improvement efforts aimed at developing new, superior tropical/subtropical ornamental germplasm, focusing on the tropical shrub genus Portlandia, the flowering tree genus Tabebuia, queen’s crape myrtle (Lagerstroemia speciosa) and the bulb crop Hippeastrum (amaryllis). Objective 4 will determine the effects of different fertilizer regimens on selected subtropical/tropical bulb crops and cycads, and the effects of different light regimens on selected species of ornamental palms. These research objectives fill the gaps of insufficient genetic and genomic characterization, and contribute to the improvement of production systems of subtropical/tropical ornamental crops.
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.