In vitro conservation of Agave sisalana germplasm under slow growth conditions

Abstract The increasing demand for natural hard fibers has stimulated sisal (Agave sisalana) fiber production and exportation. Plant germplasm conservation is essential to preserve their genetic diversity and it is a vital tool for plant selection, breeding, and in vitro propagation. This work aimed to evaluate the effect of the osmotic regulator’s mannitol and sorbitol, as well as the growth regulator paclobutrazol on A. sisalana in vitro morphological responses and to develop in vitro conservation protocols for this species. The in vitro conservation of A. sisalana was evaluated with two experiments: I – with sorbitol and mannitol, at concentrations of 0; 87; 174 and 261 mM, and with 87 mM sucrose, corresponding to the osmotic potentials of -0.217; -0.437; -0.655 and -0.873 MPa, and II – with paclobutrazol (PBZ) at concentrations of 0; 3; 6; 9; 12 and 15 μM. Mannitol at 261 mM (-0.873 MPa) promoted the slowest growth of sisal plants in vitro, with growth reduction of 288.6%, when compared to the control treatment. Furthermore, this treatment did not affect the percentage of plant regeneration and multiplication after 12 months of cultivation. Paclobutrazol at 15 µM promoted a reduction of 93.5% in plant height, when compared to the control, and did not restrict plant regeneration and multiplication percentage. Mannitol and paclobutrazol can be used with efficiency for in vitro conservation, maintaining explant viability and plant survival after acclimatization. In addition, these treatments did not cause phenotypic variations of genetic origin. This is the first study reporting strategies for in vitro germplasm conservation of A. sisalana.