Profiling key Factors Effective for Microtuberization and Nuclear Seed Production in Potato (Solanum tuberosum L.)

Abstract

The present investigation was carried out in the Department of Botany, University of Rajshahi, Rajshahi, Bangladesh with an aim to studying some of the key factors most effective for microtuberization in potato and field evaluation of the induced micro tubers towards nuclear seed production for commercial utilization. Plant materials for all experiments were obtained from Potato Tissue Culture Bank, at the Plant Breeding and Gene Engineering Laboratory, in the Department of Botany, University of Rajshahi, Bangladesh. The cultivars studied were a) All Blue, b) Diamante, c) Atlanta, d) Shaped and e) Shilbilaty (an indigenous cultivar). In the first attempt, different sugar types were evaluated on microtuberization efficiencies of potato and sucrose was considered to be the best sugar type as compared to glucose and maltose. Among the four levels, 8% sucrose in media was optimized since this level produced larger micro tubers than the micro tubers obtained from other sucrose concentrations and in this respect All Blue, Diamante and Shilbilaty performed equally well. The media with 5 µM JA resulted the highest number and maximum yield of micro tubers than the other growth regulators used and high nitrate content (HH and LH ) media increased the micro tuber size. The application of 2.0 mg/1 AgNO3 in media was found effective in microtuberization than the untreated counterpart. Among the varied organic acids treated with micro tuber media under different photoperiodic incubations, it was found that prop ionic acid added media favored the in vitro micro tuber formation under 8 h photoperiod. Microtuberization in liquid media followed by incubation at 8 h photoperiod promoted the number and fresh weight of micro tubers than the other physical supports ( agar based, liquid plus cotton and liquid plus sponge) and incubations (0, 8 and 16 h). The microtuberization media with 5 µM JA and 8 h light period were noted best in all micro tuber parameters. The 8 h pre-illumination produced the higher number of sessile micro tubers than O and 16 h periods. The incubation temperature of 15'C also yielded significantly more sessile tubers than the cultures incubated at 20 and 25'C. On the other hand, sprouting of micro tubers was more pronounced at 20'C storage temperature than 5 and 15'C storage after 12 weeks and Shee diameter) showed significantly higher survival capacity than smaller micro tubers (0.3-0.4 cm diameter). The dormancy termination and sprouting efficiencies of micro tubers were noted best in media with GA3 (100 ppm) treatment, large size of micro tubers and dark incubation. The biochemical properties of micro tubers were also investigated and noticed that the micro tubers grown in media with 5 µM JA showed maximum accumulation of total sugar, reducing sugar and starch. The vitamin C content of micro tubers decreased with the extended storage periods. Different types of in vitro experiments were conducted to find the optimum conditions of micro tuber formation and varied results were found and concluded that the media with 8% sucrose, 5 µM JA and 8 h photoperiod showed better performances in respect of number, size and yield of micro tubers. The gibberellic acid was found best in dormancy termination and sprout growth enhancement. JA in micro tuber induction media did not enhance nuclear seed production whereas 8 h light induced micro tubers had significant after effect on the plant growth and nuclear seed production in field. exhibited the highest sprouting. The survival rate of micro tubers was found to depend on micro tuber size. The larger micro tubers (0.5-0.6 cm diameter) showed significantly higher survival capacity than smaller micro tubers (0.3-0.4 cm diameter). The dormancy termination and sprouting efficiencies of micro tubers were noted best in media with GA3 (100 ppm) treatment, large size of micro tubers and dark incubation. The biochemical properties of micro tubers were also investigated and noticed that the micro tubers grown in media with 5 µM JA showed maximum accumulation of total sugar, reducing sugar and starch. The vitamin C content of micro tubers decreased with the extended storage periods. Different types of in vitro experiments were conducted to find the optimum conditions of micro tuber formation and varied results were found and concluded that the media with 8% sucrose, 5 µM JA and 8 h photoperiod showed better performances in respect of number, size and yield of micro tubers. The gibberellic acid was found best in dormancy termination and sprout growth enhancement. JA in micro tuber induction media did not enhance nuclear seed production whereas 8 h light induced micro tubers had significant after effect on the plant growth and nuclear seed production in field.