Hyperhydricity control of in vitro shoots of Turbinicarpus valdezianus (M鰈ler) GL & F

Turbinicarpus valdezianus is a species under special protection, according to the current law NOM-059-ECOL-2010. It spreads preferably through shoot proliferation in vitro. A common problem associated with the propagation of this species by tissue culture is the hyperhydricity or excess of water accumulation in the tissues of shoots explants. The literature on this topic indicates that such response is related with oxidative stress. Because of this, the effects of inhibitors of the gibberellins [paclobutrazol (PBZ) and calcium prohexadione (PCa)] and salicylic (SA) and benzoic acids (BA) were tested to diminish the hiperhydrycity of the sprouts, which was measured after twelve weeks of study initiation. The treatment with PBZ (3.4 x 10-4M) completely eliminated hyperhydricity in the sprouts, and significantly increased the organogenesis, with 18 sprouts per explant, in comparison to the 3.55 sprouts per explant observed on the control. In addition to this, PBZ induced several morphological changes in the regenerated material, including a drastic reduction in height and an increase on the thickness of stem and roots. In contrast with these observations, including PCa (10-4M), SA (10-4M) and BA (10-4M) resulted in higher hyperhydricity of shoots when compared to the control. However, they modified the number and length of roots in the sprouts, increasing the survival of the regenerated plantlets when transferred to ex vitro conditions. The histological analysis of the hyperhydric plants showed an increase in the number, diameter, and area of xylem vessels.