Effect of gelling agents on in vitro development of Amelanchier canadensis ‘Rainbow Pillar’

Production of pathogen-free woody propagation material with required genetic properties has worldwide been based on the micropropagation (Kozai & Kubota, 2001). The price of in vitro propagated plantlets – especially woody plants is relatively high due to the specifi c technology elements. Each attempt, which results in increased propagation rate, greater rate of high quality plants or decreased loss during acclimatization can reduce the cost of in vitro propagated plantlets (Kozai & Kubota, 2001). Although liquid medium can be used effectively in automated micropropagation systems (Krueger et al., 1991; Robacker & Simonton, 1992), the solidifi cation of medium seemed to be necessary in traditional systems, because using of liquid medium resulted in hyperhydric shoots in Amelanchier x grandifl ora Rehd. ‘Princess Diana’ when cultures were continuously in contact with medium (Krueger et al., 1991). Because of its stability, high clarity, non-toxicity and metabolic inactivity the agar extracted from red algae has been the most frequently used for gelling media (McLachlan, 1985). Even though the cost of medium preparation constitute a small part of the total cost (George, 1996), components of the medium is quite expensive to obtain, especially the plant tissue culture tested agaragar, which has commonly used for woody plants (Kumar Goel et al. 2007). Alternatives including Isubgol (the husk derived from the seeds of Plantago ovata), Guar gum (galactomannan derived from the endosperms of Cyamopsis tetragonoloba), several type of starches (wheat, cassava, corn, potatao, sago etc.) and other additives (bagasse, Xyloglucan extracted from seeds of Hymenaea courbaril etc.) have been studied in several experiments to fi nd a cheaper solution for gelling media (Babbar and Jain, 1998; Naik and Sarkar, 2001; Lima-Nishimura et al., 2003; Mohan et al., 2004; Babbar et al., 2005). Several blends of agar and its cheap alternatives (guar gum, isubgol and xanthan gum) were evaluated, and none of them had rheological properties comparable to agar gelled medium. However, responses of Albizzia lebbeck tissue culture to majority of blends were the same or even better than the control (agar) (Jain-Raina & Babbar, 2011). Each types of gelling agents (Plant Agar, Gelcarin GP-812, Guar gum, Isubgol) was effective in micropropagation of blackberry (Rubus laciniatus ‘Thornless evergreen’), however the highest multiplication rate was achieved on medium gelled with Plant Agar, while plantlets grown on medium solidifi ed by Guar gum were extremely vigorous and well developed (Fira et al., 2010). Blends of agar and guar increased the number of regenerated shoots in micropropagation of pear (Pyrus communis L., ‘Durondeau’) compared to media solidifi ed by agar (Lucyszyn et al., 2006). Mixtures of agar and Isubgol also were effective in in vitro regeneration of potato and Stevia provided that the rate of Isubgol in the mixture does not exceed 50% (Khan et al., 2012). Effect of gelling agents on in vitro development of Amelanchier canadensis ‘Rainbow Pillar’