Germination in vitro, micropropagation, and cryogenic storage for three rare pitcher plants: Sarracenia oreophila (kearney) Wherry (federally endangered), S. leucophylla Raf., and S. purpurea spp. venosa (Raf.) Wherry

Abstract

The genus Sarracenia forms a group of carnivorous pitcher plants native to North America. Habitat destruction and overcollection have caused pitcher plants to become rare, including U.S. federally endangered S. oreophila as well as S. leucophylla and S. purpurea spp. venosa (Raf.) Wherry, both listed as endangered in several states. Protocols for in vitro germination, sustainable shoot micropropagation, shoot establishment in soil, and seed cryopreservation are presented. Six-min sulfuric acid scarification treatments coupled with appropriate tissue culture media resulted in germination in vitro within 3 weeks, often reaching greater than 50%. Best germination for S. leucophylla and S. purpurea occurred on one-third strength Murashige and Skoog (MS) salts, whereas S. oreophila germinated best on one-sixth strength MS salts. Adjustment of pH to 4.5 to simulate a bog environment further increased germination for S. leucophylla. Shoot multiplication occurred at optimal levels when explants were placed on media in the presence of a cytokinin without auxin with greatest multiplication on 6-benzylaminopurine (BAP) or trans-zeatin and best shoot quality on trans-zeatin. Plant establishment in soil required both an in vitro rooting treatment and use of shoot clusters resulting in greater than 80% survival in soil. Seed cryopreservation tests with all three species suggest storage in liquid N2 followed by in vitro micropropagation and plant establishment can be used to preserve material long term.