Tea (Camellia sinensis) has the potential to be cultivated as a commercial crop in the United States, but growers need access to clean plant material. The wholesale value of tea in the United States was $13.6 billion in 2022, yet less than 100 acres of tea are currently grown here. Tissue culture can be a means to provide disease-free and genetically identical plants. Three experiments were carried out using explants, which are 2.5 cm stems with single, active nodes from the young shoots of 28-year-old ‘Minto Pacific’ plants. Experiment 1 tested chemo- and thermotherapy: 40 explants were placed in Murashige and Skoog (MS) medium supplemented with 2, 4-dioxo-hexahydro-1-3-5 triazine (2 mL/L), aspirin (1.4 mL/L), and ribavirin (1.5 mL/L). Explants were placed in a growth chamber at 25 ± 1 ℃ on a 16-h photoperiod for 4 to 5 weeks, then subcultured and placed in an incubator for an additional 4 to 5 weeks set at 32 to 35℃ on the high end/light period and 28 to 30℃ on the low end/dark period (alternating every 4 h). All explants were either contaminated or dead, potentially due to high temperatures, by the end of this 8 to 10 week cycle. Experiment 2 evaluated use of meristems, which were excised from axillary buds of the aforementioned young shoots of 28-year-old ‘Minto Pacific’ plants and placed on MS media supplemented with 6-benzylaminopurine (1 mL/L) and gibberellic acid (0.5 mL/L). Explants were placed in a growth chamber at 25 ± 1 ℃ on a 16-h photoperiod. Of the 10 meristems, there was no contamination, but only one meristem has survived long-term (5 months). With Experiment 3, explants (n=26) were soaked in 4% v/v Plant Preservative Mixture (PPM) for 2 h, then transferred to MS medium, before being placed in a growth chamber at 25 ± 1 ℃ on a 16-h photoperiod. Contamination and physiological disorders developed over time, leaving only one visually healthy explant after 5 months. The effect of PPM as a soak or a growth medium-additive needs to be further investigated through additional experiments.
