Optimizing In vitro Callus Induction from Spathiphyllum Leaf and Petiole Explants

Spathiphyllum species are globally renowned ornamental houseplants, appreciated for their elegant foliage and air-purifying properties. Conventional methods of propagation such as rhizome division are labour-intensive, slow and inadequate for meeting the commercial demand for uniform and disease-free plant material. To address these limitations the present study developed an efficient in vitro regeneration protocol using leaf and petiole explants derived from cultured Spathiphyllum plantlets. These explants were selected due to their non-destructive nature, sterility and regenerative capability. Explant viability remained consistently high (>90%) across treatments. Notably, callus formation—a crucial intermediate stage in indirect plant regeneration—was significantly influenced by the type and concentration of plant growth regulators (PGRs). The highest frequency of callus induction (53.80 %) was recorded on MS medium enriched with MS + 3.0 mg L⁻¹ BAP and 1.0 mg L⁻¹ 2,4-D (C5), with visible callus emerging within 151.40 days. Interestingly, leaf explants exhibited no callus initiation under any tested condition, although they maintained high survival rates. Remarkably, a novel regeneration pathway was developed wherein petiole explants produced somatic embryos under continuous dark incubation on MS medium containing TDZ and 2,4-D which later transitioned to light for embryo maturation. A unique aspect of this protocol is the extended (3–4 months) dark incubation period without subculturing, which may induce somatic embryogenesis by activating stress-related developmental cues. The results confirm the potential of this method as a reliable platform for large-scale propagation of Spathiphyllum, enabling the production of uniform, commercially viable plants.