Influence of gelling agent and cytokinins on the control of hyperhydricity in Aloe polyphylla

Abstract

Shoot regeneration and occurrence of hyperhydricity in Aloe polyphylla were greatly affected by the type of gelling agent. The use of gelrite resulted in a significantly lower multiplication and almost four times higher hyperhydricity (65%) compared to agar-solidified medium. Gelrite was further selected to evaluate if hyperhydricity can be overcome by altering the physical properties of the gel, as represented by increasing gelrite concentrations. Four concentrations of gelrite (0, 2.4, 6 and 16 g l -1 ) were tested in combination with zeatin, N 6 -benzyladenine (BA) or thidiazuron (TDZ). Almost all explants grown in liquid media in the presence of cytokinins became hyperhydric and lost their ability to regenerate. The greatest shoot formation was obtained on media with 2.4 g l -1 gelrite and 5 lM zeatin or BA, however hyperhydricity was very high. Satisfactory reduction in hyperhydricity was achieved only at 16 g l -1 gelrite, under which conditions the multiplication also decreased. The use of TDZ resulted in very low shoot regeneration and high hyperhydricity irrespective of the gelrite concentration.

Influence of 6-Benzyladenine and gelling agent on the reduction of hyperhydricity in Tectona grandis L.

“…Similar results were reported for Malus domestica (Pasqualetto et al, 1988), Allium cepa (Jakse et al, 1996) and Scrophularia yoshimurae (Tsay et al, 2006). However, in agreement with Ivanova and Van Staden, (2010), we assumed that this effect of the gelling agent on the proliferation rate appears to be species-specific because more shoots were produced on media with agar of A. polyphylla.…”

“…In our results, a negative side effect of the gelrite concentration was not observed, maybe because the amount of gelrite added from one treatment to another was low. Similar results were also reported for A. polyphylla (Ivanova and Van Staden, 2010). These authors report that increasing the gelrite concentration, and so decreasing the water availability in the media, reduced significantly the occurrence of hyperhydricity.…”

“…Gelrite promotes hyperhydricity in teak and similar results have been found with various species Ivanova and Van Staden, 2010). The hypothesis about the effect of gelrite on hyperhydricity seems to be related to its physical structure as supported by Ivanova et al, (2006).…”

“…Because substantially smaller quantities produce gels of hardness comparable to agar, gelrite appears to be an economically good gelling substitute for agar (Ivanova and Van Staden, 2010).…”

Direct shoot induction ofPaeonia lactiflora‘Zhong Sheng Fen’ and rejuvenation of hyperhydric shoots

“…These losses, together with the poor survival rate of hyperhydric shoots when transferred to ex vitro conditions, limit the potential of in vitro techniques for mass propagation (Ivanova & van Staden 2008). Hyperhydricity is a complex phenomenon that is affected by several factors such as: medium (An 2005); explant age (Bouza et al 1994); temperature (Chu & Li 1993); light (Guo 2001); subculture age (Guo 2001); the type of gelling agent and cytokinins (Ivanova & van Staden 2011); nitrogen source, concentration and the NH 4…”