Factors influencing in vitro establishment of mango shoot buds.
Chandra R., Padaria J. C., Shubhra Srivastava
Author Affiliation: Biotechnology Laboratory, Division of Crop Improvement and Production, Central Institute for Subtropical Horticulture, Rehmankhera, Lucknow - 227 107, India.
Indian Journal of Plant Physiology 9 : 136-144
Abstract : Mango shoot bud explants taken directly from field-grown mature tree face major problems of phenolic exudation and deep seated contamination in the establishment of aseptic cultures. Due to these problems, the explants do not survive long enough to respond to cultural conditions. The problems of phenolic exudation and microbial contamination were overcome using various sequential pretreatment and different sterilizing agents. The shoots were defoliated in the field and sprayed with disinfectant solution (0.1% bavistin [carbendazim] + 0.1% gentamicin) followed by 2 mg/litre BA [benzyladenine] + 2 mg/litre GA3 [gibberellic acid] every alternate day up to 15 days. The shoots were placed in an antioxidant solution (ascorbic acid 70 mg/litre + citric acid 50 mg/litre) and kept for 30 min. This was followed by running tap water treatment for 2 h and stirring in PVP (0.5%) for 1 h. This treatment was followed by sequential sterilization with 2-3 drops of Tween-20 drops of Tween-20 in distilled water for one h, rinsing with 70% alcohol for 30 seconds and 0.1% HgCl2 treatment for 12-15 min. before inoculation on the medium. Subculturing into fresh medium was done every alternate days up to one week and then weekly. Using these methods, 80% sterile cultures were obtained. These cultures remained green for 8-10 weeks on MS basal medium supplemented with 3 mg/litre indole acetic acid + 1 mg/litre kinetin + 200 mg/litre adenine sulfate + 1 mg/litre thiamine + 1 mg/litre riboflavin + 100 mg/litre casein hydrolysate + 400 mg/litre glutamine + 100 mg/litre PVP + 100 mg/litre ascorbic acid + 60 mg/l sucrose. Shoot buds of cv. Amrapalli showed the best response with 48.92% cultures remaining green and with the opening of leaf primordial even after 4 weeks of inoculation. Differentiation of shoot buds into plantlets was achieved but plantlets did not grow beyond the 3-4 leaf primordial stage.