Plant growth regulators (RCV), Microshoots, Bromeliads, Tropical forest, Endangered species
Objective: To develop a protocol for the aseptic in vitro establishment and multiplication of Aechmea fasciata (Lindl.) Baker.
Design/Methodology/Approach: Different concentrations of NaClO (2, 3, 4, and 5%) were assessed for the aseptic establishment of A. fasciata. During the shoot induction stage, the three following treatments were tested: T1 = 6-benzyladenine + naphthalene-1-acetic acid (BA + ANA; 5 + 2 mg L-1); T2 = zeatin + 2,4-dichlorophenoxyacetic acid (Zea + 2,4-D; 5 + 2 mg L-1); and T3 = control with no plant growth regulators. During the shoot multiplication stage, three more treatments were assessed: T1 = Zea + 2,4-D (2.5 + 1 mg L-1); T2 = Zea + 2,4-D (5 + 2 mg L-1); and T3 = Zea + 2,4-D + gibberellic acid (AG3) (2.5 + 1 + 3.5 mg L-1). To assess the number of cellular events, different nitrate concentrations were tested in the medium (18.8, 39.4, and 60 mM NO3-). Finally, during the shoot regeneration stage, nine treatments derived from the combination of three concentrations of kinetin (KIN: 0, 0.1, and 0.5 mg L-1) and of indole-3-acetic acid (AIA: 0, 0.3, and 0.4) were assessed. Completely randomized designs were used in each stage. Duncan’s test (p ≤ 0.05) was used to compare the means during the shoot induction and multiplication stages. A regression analysis was carried out to study the aseptic establishment and a non-parametric test (Kruskal-Wallis) was made to assess the “amount of microshoots during regeneration” variable.
Results: A. fasciata aseptic explants with 4% NaClO were established. Shoot induction was most effective with the BA + ANA (5 + 2 mg L-1) treatment. The highest callus production was reported with the Zea + 2,4-D (5 + 2 mg L-1) treatment. The largest number of microshoots was obtained with high nitrate doses. Meanwhile, the most successful regeneration was achieved with the 0.1 mg KIN L-1 and 0.4 mg AIA L-1 treatment.
Study Limitations/Implications: The application of Zea and 2,4-D during multiplication induced callus formation.
Findings/Conclusions: Apical bud explants in an MS medium with BA and ANA present organogenesis. The use of Zea and 2,4-D forms calluses in the already established in vitro shoots, which regenerate with the use of KIN and AIA. Better microshoot coloring and development were achieved with MS salts, which have a medium nitrate content.