Contamination control in Iranian seedless barberry micropropagation

Abstract

Iranian seedless barberry is a species with high degree of contamination in <em>in vitro</em> culture. The current study was aimed to investigate the effects of mercuric chloride (HgCl₂), sodium hypochlorite (NaOCl) + HgCl₂, HgCl₂ + 8-hydroxyquinoline, cefotaxime + streptomycin, HgCl₂ + shoot type, HgCl₂ + explant position and HgCl₂ + shoot color on the reduction of contamination. The results showed that the combined use of NaOCl and HgCl₂ was more effective than their single use, but the contamination rate was relatively high. Interestingly, the results showed that explants sterilized with 100 mg/L HgCl₂ and cultured in the medium containing 150 mg/L 8-hydroxyquinoline exhibited the lowest fungal contamination (15%), while those treated with 50 mg/L HgCl₂ and cultured in the 8-hydroxyquinoline-free medium showed the highest fungal contamination (96%). Furthermore, treatment of 75 mg/Lcefotaxime + 70 mg/L streptomycin exhibited no bacterial contamination compared to the control with 58% bacterial contamination. Explants prepared from suckers and treated with 150 mg/L HgCl₂showed the lowest rates of fungal (16%) and bacterial (13%) contamination. The results also showed that explants collected from upper position had the lowest rates of fungal (20.87%) and bacterial (18.4%) infection. Explants taken from pinkish-colored shoots showed surprisingly the lowest rates of fungal contamination (13.33%), bacterial contamination (10%) and bud mortality (36.47%). In general, choice of explants from upper position of pinkish-colored suckers, sterilization of them with 100 mg/L HgCl₂for 5 min and their culture in medium containing 150 mg/L 8-hydroxyquinoline can be recommended for reducing the contamination.