Efficient In Vitro Regeneration of Gladiolus grandiflorus L. Through Direct Organogenesis and Somatic Embryogenesis

Abstract

Gladiolus grandiflorus is an economically important ornamental geophyte with a low multiplication rate and high susceptibility of corms to fungal infection under field conditions, thus limiting the availability of healthy planting material. Therefore, the development of an efficient in vitro regeneration system is essential for rapid clonal propagation and disease-free plant production. This study established an efficient regeneration system using corm explants. Direct regeneration was achieved, with the highest shoot induction frequency (83.33%) obtained on Murashige and Skoog (MS) medium fortified with 0.5 mg/L 6-benzylaminopurine (BAP) and 0.5 mg/L 1-naphthalene acetic acid (NAA), and the maximum number of shoots (4.03 shoots per explant) was recorded at 1.0 mg/L BAP. The first report of this cultivar included high-frequency direct somatic embryogenesis induced on MS medium containing 2 mg/L BAP and 2 mg/L NAA. The embryogenic origin of somatic embryos was confirmed by scanning electron microscopy and histological analyses. Plantlet conversion and rooting were observed on MS medium containing 2.0 mg/L BAP plus 1.0 mg/L NAA and 1.0 mg/L indole-3-butyric acid, respectively, with an ex vitro survival rate of 83%. Flow cytometry showed comparable 2C nuclear DNA contents (33.58–33.61 pg) among regenerated plantlets and the field-grown (mother plant), indicating ploidy stability. Start codon targeted marker revealed 95.13% genetic similarity with predominantly monomorphic banding patterns, confirming clonal fidelity. The established regeneration system provides an efficient approach for the production of disease-free and genetically stable G. grandiflorus plants.