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Florida is home to 106 native orchid species, of which 77 are listed as endangered or threatened by the State of Florida. The Institute for Regional Conservation (IRC) has classified 62 of these species as either critically imperiled, imperiled, or rare in South Florida. Because of lack of endosperm, orchid germination rates are very low in nature, as they depend on an obligate relationship with mycorrhizal fungi for nutrients. Most orchid seeds can be germinated in vitro without the need for specific mycorrhizal fungi. This study aims are to establish a fast and efficient protocol for in vitro seed germination using different nutrient media and plant growth regulator (PGR) combinations, and to optimize seedling acclimatization protocols using different greenhouse media. To determine germination preferences, three different in vitro seed germination media were tested supplemented with PGRs, including 1) Murashige & Skoog (MS) (control), 2) MS supplemented with 1.5 mg/L 6-benzylaminopurine (BAP), and 3) MS supplemented with 1 mg/L BAP and 0.5 mg/L 1-Naphthaleneacetic acid (NAA) on Cyrtopodium punctatum, a state-listed endangered, IRC critically imperiled epiphytic orchid. There was no significant difference amongst the treatments after 2 and 6 weeks of seed sowing culture. To understand post-culture survivorship, two epiphytic and one terrestrial native species (Trichocentrum undulatum, Encyclia tampensis, and Oncidium ensatum) were chosen for the acclimatization study with two commercially available potting substrates (coir, sphagnum). To measure seedling growth rates, phenotypic measurements [leaf number, leaf length, root length, plantlet height, light intensity, pH, and electrical conductivity (EC)] and Soil Plant Analysis Development (SPAD) and Normalized Difference Vegetation Index (NDVI) values were recorded monthly for five months. All media/PGR combinations resulted in an initial high percentage of stage I growth but inhibited Protocorm-like bodies (PLBs) development, suggesting more research is necessary to determine later improvements or detriments to MS basal media with BAP and NAA. Comparing acclimatization media with the three species of orchid chosen for this experiment, neither O. ensatum nor E. tampensis showed a marked preference for sphagnum moss or coir. However, T. undulatum did perform better with coir compared with sphagnum. This research will help botanical gardens and commercial plant tissue culture laboratories to have a better understanding on selection of PGR combinations for in vitro cell culture and acclimatization media on increasing the viability and plant health and decreasing the mortality of endangered plants.

Myrciaria dubia (caçari or camu-camu) is a species with great relevance because of its high levels of bioactive compounds and antioxidant activity. The species is propagated mainly by seed, which leads to high genetic diversity. Producing plants that maintain their characteristics on a large scale at a low cost is a challenge for fruit species, especially in the Myrtaceae family. Therefore, this study aimed at assessing the effects of different plant growth regulators at various concentrations for the induction of somatic embryogenesis from caçari nodal segments and leaf disk explants. Two independent experiments were performed using nodal segments and leaf disks from plants grown in the greenhouse. In the first experiment, the combined effect of auxin and cytokinin at different concentrations was evaluated: 2,4-dichlorophenoxyacetic acid at 0, 1, 2, and 4 mg⋅L^–1; and benzylaminopurine at 0, 0.25, 0.5, and 1 mg⋅L^–1). In the second experiment, the application of different plant growth regulators (benzylaminopurine, kinetin, thidiazuron, and isopentenyl adenine) and their concentrations (0, 2, 4, and 6 mg⋅L^–1) were evaluated. In both experiments, the basic culture medium was woody plant medium. Callus formation via nodal segments and leaf disks occurred in the first 30 d from cultivation and proved to be responsive to induction by 2,4-dichlorophenoxyacetic acid and benzylaminopurine. Auxin proved to be essential for somatic embryogenesis induction in nodal segments using 1 and 4 mg⋅L^–1 of 2,4-dichlorophenoxyacetic acid alone. The results of this experiment will help advancing protocols for regeneration of somatic embryos and elucidating the physiological, molecular, and genetic mechanisms involved in the process of somatic embryogenesis for M. dubia. The development of an efficient protocol for in vitro clonal propagation of this species also lays the groundwork for further optimization of the system for genetic transformation.