Location: Subtropical Horticulture Research2021 Annual Report
Objective 1: Efficiently and effectively maintain the safety, genetic integrity, health, and viability of subtropical and tropical ornamental genetic resources, and distribute them and associated information worldwide. Subobjective 1A: Strategically expand and improve collections of priority tropical and subtropical ornamental taxa and associated information. Subobjective 1B: Conserve, regenerate, and distribute as needed subtropical and tropical ornamental genetic resources and information efficiently and effectively, emphasizing priority genera identified by Crop Germplasm Committees (CGCs). Objective 2: Develop more effective genetic resource characterization, phylogenetic analyses, and evaluation methods, and apply them to priority subtropical and tropical ornamental genetic resources. Record and disseminate evaluation and characterization data via GRIN-Global and other data sources. Subobjective 2A: Develop nearly complete whole plastome and low copy nuclear gene sequences to generate well-resolved phylogenies of various clades of Amaryllidaceae. Subobjective 2B: Elucidate the genetic control of anthocyanin pigmentation in the genera Hippeastrum (amaryllis), Worsleya, and Griffinia, and fragrance production in Hippeastrum. Objective 3: Guided by new knowledge of the genetic relationships and valuable ornamental traits of poorly-known plants, develop superior new cultivars and genetically-enhanced populations and/or selections of priority subtropical and tropical ornamental crops. Subobjective 3a. Select, breed, and/or release new cultivars of the subtropical/ tropical shrub Portlandia, the flowering tree genus Tabebuia (inc. Handroanthus), and other tropical/subtropical taxa. Subobjective 3b: Continue evaluation and selection of Hippeastrum hybrid progeny.
The long term objectives of this project are to ensure a secure and diverse stream of new genetic variation and enhanced germplasm for the subtropical/tropical ornamental horticulture industry as well as generate and consolidate detailed information about the intrinsic genetic variability, systematic relationships, and ornamental merit of genetic resources via genetic characterization, systematic studies, and field evaluation. These objectives are a combination of hypothesis-driven and non-hypothesis driven research. The objectives form an integrated program of subtropical/tropical ornamental germplasm characterization, enhancement and improved management practices. The program efficiently and effectively maintains the safety, genetic integrity, health, and viability of subtropical and tropical ornamental genetic resources. Collections of priority tropical and subtropical ornamental taxa and associated information will be strategically expanded and improved, distributing them worldwide to customers and stakeholders, emphasizing priority genera identified by appropriate Crop Germplasm Committees. Nearly complete whole plastomes and many low copy nuclear gene sequences will be obtained to generate well-resolved phylogenies of various clades of Amaryllidaceae. The genetic control of anthocyanin pigmentation in the genera Hippeastrum (amaryllis), Worsleya, and Griffinia, and fragrance production in Hippeastrum will be elucidated. Guided by new knowledge of the genetic relationships and valuable ornamental traits of poorly-known plants, superior new cultivars and genetically enhanced populations and/or selections of priority subtropical and tropical ornamental crops will be developed, with emphasis on the tropical shrub Portlandia, the flowering tree genus Tabebuia (inc. Handroanthus), and other tropical/subtropical taxa. The evaluation and selection of Hippeastrum hybrid progeny will be continued. Hybrid progeny from the past few years, many of which are just reaching flowering size, will be evaluated for floral phenotype and flowering behavior, with selections made based on novel flower coloration, patterning, fragrance, and both bud and scape number.
The ornamental plant industry is one of the most diverse and fastest growing business in Florida. The 2017 wholesale and retail sales sectors of the ornamental horticulture industry in Florida generated total output sales of $21.08 billion, 232,648 jobs, $8.75 billion in employee earnings, and $13.17 billion in value added benefits. ARS scientists in Miami, Florida, conducted genetic characterization, improvement, and best horticultural management practices for subtropical/tropical ornamental germplasm. With the recent hire of the Lead Ornamental Geneticist, germplasm curation, restoration, genetic characterization, improvement and best horticultural management practices for subtropical/tropical ornamental germplasm is progressing well. The superior genetic selections of F1 Portlandia plant hybrids (P. grandiflora X P. coccinea), developed in this project were transplanted in various fields for multi-location trait observations and analysis. For Amaryllidaceae phylogenomics, ARS scientists in Miami, Florida, developed a super matrix that included, 524 nuclear genes totaling 730,500 base pairs (bps) and partial plastome sequences of about 122,549 bp. To elucidate the genetic control of Amaryllidaceae flowering pigmentation, ARS scientists in Miami, Florida, analyzed transcriptome sequencing of targeted flowering tissues and created primers for candidate genes. The survey for genes present in white and purple colored Amaryllidaceae flowering plants are in progress. Rigorous ornament plant management, efficient national and international distribution of germplasms through Germplasm Resource Information Network Global (GRIN-Global), close collaborations with local ornamental organizations, as well as academic researchers and responding to immediate customer demands are progressing well.
1. The Amaryllidaceae family consists of 1300 species with most vibrant and large showy flowers. Amaryllis species are primarily distributed in the tropical and sub-tropical regions of the world and lack genetic characterization that can be useful to the ornamental industry. ARS scientists in Miami, Florida, developed one of the largest DNA sequence data sets for the Amaryllidaceae plants. The molecular study successfully unlocked the genetic relatedness and purity of four tribes Clinantheae, Eucharideae, Eustephieae and Hymenocallideae in Amaryllidaceae with robust phylogenetic analysis. For Amaryllidaceae flowering pigmentation work, deep transcriptome (messenger RNA molecules expressed from the genes of the plant) analysis was conducted using various high throughput bioinformatics tools. The analysis recorded gene families that are comparable across different plant species. These research findings have advanced the taxonomical classification and gene functions of an important group of flowering Amaryllidaceae. Fifteen amaryllis hybrids were released and three commercial ornamental growers have requested the materials. The release of these cultivars directly enhances the availability and expansion of an important ornamental flowering plant for the domestic and international market.
Meerow, A.W., Gardner, E., Nakamura, K. 2020. Phylogenomics of the andean tetraploid clade of the american amaryllidaceae (sbfamily amaryllidioideae): unlocking a polyploid generic radiation abetted by continental geodynamics. Frontiers in Plant Science. 11: 582422. https://doi.org/10.3389/fpls.2020.582422.