Protocol for shoot proliferation and regeneration of a salt-tolerant plant, Thuarea involuta

Thuarea involuta , a perennial herb that often grows on sandy beaches, has documented salt and drought tolerance, making it a useful plant species for the stabilization of island reefs. However, there are no protocols for its large-scale propagation, so effective in vitro protocols can assist to mass propagate healthy plants for ecorestoration. In this study, T. involuta stem segments were used as explants to establish a highly efficient in vitro shoot proliferation and regeneration system for the first time. The shoot proliferation coefficient (SPC) was highest when thidiazuron was used alone (SPC = 8.78) relative to the use of kinetin (KIN) or 6-benzyladenine (SPC = 6.53 and 8.30, respectively). Multiple shoots were proliferated on Murashige and Skoog (MS) medium supplemented with 1.0 mg L −1 BA and 0.1 mg L −1 α-naphthaleneacetic acid, leading to a SPC of 9.64 within 30 days. After individual shoots were transferred to MS medium with or without indole-3-butyric acid (IBA) or α-naphthaleneacetic acid (NAA), all formed roots within 15 days. In vitro plantlets transplanted to a peat and vermiculite (1:1) substrate displayed 96.67% survival after 60 days. When MS medium was supplemented with 1.0 mg L −1 2,4-dichlorophenoxyacetic acid and 1.15 g L −1 proline, callus was effectively induced from the base of shoots; 90% of callus differentiated into adventitious shoot buds on MS medium containing 0.1 mg L −1 KIN. This study provides a useful set of in vitro protocols for the practical mass propagation of plants that can be used in sand dune ecorestoration, or to avoid the erosion of beach sand by sea water.