Strategies for the micropropagation of bromeliads

Bromeliads are tropical plants that are native to the Americas with a wide distribution in the rain forests, deserts and coastal areas. They are mostly epiphytes and terrestrial, diverse and important from the ecological point of view, they are found in microhabitats in strong interactions with fauna. Most of the ecosystems where they naturally occur are now endangered. Bromeliads are also one of the bases of the ornamental industry worldwide, being commercialized according to the features and colour of the foliage and flowers. This industry relies also on breeding programmes generating new hybrid bromeliads with improved bloom and foliage. Thus, advanced propagation systems based on micropropagation are valuable tools for both bromeliad germplasm conservation and for the mass clonal propagation of a selected genotype. In this chapter, a series of in vitro regenerative protocols for bromeliad mass propagation are described in detail. Emphasis is placed on the Brazilian native species, mainly those from the Atlantic Forest biome. The morphogenetic pathway based on nodule cluster culture is stressed, as (a) it seems to be recurrent in bromeliads, (b) it results in high regenerative rates, and (c) it is easy to handle. Protocols based on somatic embryogenesis and encapsulated units using hydrogel are presented. Finally, the use of temporary immersion systems (TIS) for mass propagation is described in detail for two bromeliads: Aechmea fasciata, and Vriesea brusquensis.