Nitrogen assimilation in the bromeliad Ananas comosus var. ananassoides (Baker) Coppens & F.Leal grown in vitro with different sources of inorganic nitrogen

ABSTRACT Ananas comosus var. ananassoides (Baker) Coppens & F.Leal is a native ornamental bromeliad of the endangered biome Cerrado. Therefore, approaches aimed at the preservation of this species, such as in vitro cultivation and micropropagation are needed. Nitrogen (N) is absorbed by plants, mainly as NO3- and/or NH4+, and assimilated into amino acids. The aim of this work was to evaluate the N assimilation in this bromeliad. Plants were grown in vitro for seven months in modified MS medium with 15, 30, 60, and 90 mM of N as NO3-, NH4+ or NH4NO3, and then transferred to ex vitro conditions for acclimatization. Plants grown with NH4+ had high mortality. During acclimatization plants cultivated with 30, 60, and 90 mM of N as NH4NO3 showed higher biomass. With regard to N assimilation, GS and NR showed the highest activity in plants cultivated with NH4NO3, whereas plants cultivated with NH4+ had the highest GDH activity. Consequently, in vitro and ex vitro cultivation of this species with 60 mM N as NH4NO3 is recommended.