Crucial Role of Nitrogen in In- Vitro Regeneration of Phyllanthus Amarus Schum. and Thonn

Nitrogen plays a pivotal role in growth and differentiation of cells of Phyllanthus amarus Schum. and Thonn. Both form and amount of nitrogen in nutrient medium have significant effects on the rate of cell growth and differentiation. In this study, effects of different inorganic nutrients (KNO3 and NH4NO3) and organic nutrients (glycine) on regeneration of P. amarus were evaluated. Murashige and Skoog’s medium (MS) was used as basal medium along with plant growth hormones and different concentrations of nitrogen. Among the various growth hormones tried, BAP (0.5 mg/l) gave maximum number of shoots (17.33±0.86) after 3-4 weeks of inoculation. However, various strength of KNO3, NH4NO3 and glycine were optimized in the medium in order to get the maximum number of shoots, nodes per shoot, shoot length as well as the size of leaves respectively. Amongst all modifications, less or more, MS medium with standard amount of nitrogen source was found to be most effective. The shoots regenerated on MS medium along with BAP (0.5 mg/l) were subjected to their elongation on the same medium and their root induction was done on half strength MS medium along with IBA (0.5 mg/l). These complete plantlets were hardened and acclimatized in natural conditions. 80% survival rate was observed under field conditions. INTRODUCTION: Tissue culture technique is an alterative method to obtain rapid clonal multiplication. Growth and morphogenesis of plant tissues under in vitro conditions are largely influenced by the composition of the culture media. Mineral nutrients are one of the most important and basic components of plant tissue culture. Nitrogen assimilation and its role in plant growth and development play a pivotal role in establishing and understanding of cell differentiation in plants. Both the form and amount of nitrogen in the in vitro medium have significant effects on rate of cell growth, differentiation and cell totipotency . In plant nutrient medium, nitrate ions, ammonium salt, amino acids and complex organic compounds supply nitrogen. Nitrate ions and ammonium salts are the good sources of nitrogen because they can be absorbed and metabolized by the cells easily, which further lead to root branching, breaking of seed and bud dormancy and stop apical dominance. Hence, nitrogen in the form of NH4 + and NO3 is the dominant mineral nutrient in most plant tissue culture formulations, in both proportion and the concentration of NH4 + and NO3 . Optimization of such compounds stimulates regeneration in recalcitrant cultivars also .