Optimization of in vitro regeneration of Ferocactus peninsulae (Barrel Cactus) through transverse thin cell layer (tTCL) culture: a strategy for large-scale propagation

Ferocactus peninsulae (F.A.C. Weber) Britton & Rose, commonly known as the barrel cactus, is a distinctive and visually striking succulent belonging to the Cactaceae family. It is renowned for its impressive size and robust, barrel-shaped structure. F. peninsulae faces potential threats from habitat destruction and illegal collection. This study investigates the response of transverse Thin Cell Layer (tTCL) explants of F. peninsulae to various concentrations (0.5 to 2.0 mg L⁻¹) of two cytokinins, 6-benzylaminopurine (BAP) and 6-furfuryl amino purine (Kinetin/Kin) to induce multiple shoots in vitro. The tTCL explants were inoculated on Murashige and Skoog’s medium supplemented with 1.0 mg L⁻¹ BAP to induce fresh shoots (98.6% response). The shoots were proliferated (19.3 shoots per tTCL explant with 3.5 cm length) on a combination of BAP (0.75 mg L⁻¹) and indole-3-acetic acid (IAA; 0.15 mg L⁻¹). The results demonstrated the differential impact of cytokinins and auxins combinations on shoot multiplication, with BAP and IAA proving optimal for robust shoot growth while the higher concentrations led to abnormal morphogenesis and callus formation. The freshly generated shoots were rooted on 0.75 mg L⁻¹ indole-3 butyric acid (95.8% rooting response) and hardened in the greenhouse, and the plantlets were successfully shifted to the field with a 100% survival rate. The study could help in the large-scale production of the conservation-prioritized cactus species using the tTCL culture technique.