Explant surface disinfection is a delicate and indispensable procedure, because every subsequent step in culture must take place under sterile conditions. An optimal disinfection protocol is a compromise between the minimisation of surface microorganisms and the avoidance of tissue damage by the disinfectant. For mistletoe, these requirements can be fulfilled by treating explants in a solution of either 1% (w/ v) sodium hypochlorite for 15 min, or 0.1-0.2% (w/v) mercuric chloride for 12 or 20-25 min. Mistletoe leaf explants are generally more sensitive to surface sterilisation than stem explants.
When tissue-culturing V. album, explant browning can be an serious problem: explants develop necrotic-like areas which occasionally lead to explant decline and death, thus negatively affecting callus induction. However, depending on the disinfection protocol and the composition of the induction medium, a callus tissue can be formed on 4-12% of the declined explants and proliferate further. These callus tissues retain a black-brownish colour even after repeated subcultures.
The addition of ascorbic acid (at a concentration of 10 mg/1) to the culture medium greatly reduced the frequency of the necrotic symptoms, allowing thus for an increased callus induction (13-45% of cultured explants, depending on medium composition and explant source). These calli obtain a pink-whitish colour (Fig. 1A) and demonstrate a higher proliferation rate (expressed as callus fresh and dry weight) than the black ones (Fig. 1B). The formation of creamy-pink callus tissues has been observed by Fukui et al. (1990) as well.
Was this article helpful?
Acai, Maqui And Many Other Popular Berries That Will Change Your Life And Health. Berries have been demonstrated to be some of the healthiest foods on the planet. Each month or so it seems fresh research is being brought out and new berries are being exposed and analyzed for their health giving attributes.