Embryogenic induction of torch ginger (Etlingera elatior) callus

Abstract

Torch ginger Etlingera elatior (Jack) R.M. Smith is a tropical herb-like, rhizome-like and perennial plant that possesses inflorescences that are both pretty and showy at different colour shades, and have a great visual appeal. Producing seedlings at a high enough level when done conventionally by the division of tussocks, has high costs and phytosanitary problems. The objective of this study was to evaluate the induction of somatic embryogenesis and its potential for subsequent plant regeneration in torch ginger. Rhizomes, leaves and roots from the seedlings grown in vitro were used as explant segments. The different explants were cultured on MS medium supplemented with 30 g L-1 sucrose, and it was solidified with 5.5 g L-1 of agar. The effect of 2.4-D and picloram concentrations of 0.0, 1.0, 2.0 and 4.0 mg L-1 was studied. Astructural analysis was performed by scanning electron microscopy (SEM). Cytochemical analysis were performed to detect nucleeous with carmine acetic, starch with lugol and lipids with Sudan III, and a flow cytometry analysis to verify the stability of ploidy in the callus. Results indicate that the culture medium with 2.4-D yielded the induction of embryogenic callus with the characteristics of the rhizome segments of the explant. Regarding the ultrastructural analysis of embryogenic callus characteristics, the cells showed a similar isodiametric form as somatic embryos in the globular stage and cytochemical analysis. The presence of callus cells in pro-embryogenic explants containing each of the regulators was confirmed. In the cytometry analysis, the average DNA content of callus ranged from 5.43 to 10.15 pg, and the coefficients of variation varied between 0.3 to 2.26. Callus induced with 2.4-D showed 86 % stability, and with picloram was 64 %. The callus formation was more evident after application of 2.4 D. This is the first study of embryogenic potential in cells of the torch ginger, and showed that 2,4-D induced callus with higher starch content and genetically stable.