Efficient regeneration protocol for callus and shoot induction from recalcitrant Phaseolus vulgaris L. explants under optimum growth conditions

Callus is the most significant morphogenic response obtained in plant tissue culture studies. It can be used for micropropagation or to create transgenic lines. Phaseolus vulgaris L. (common bean) is one of the economically important crops with a great nutritional value. However, very little effort has been made to regenerate callus from P. vulgaris explants. Six explants were used namely root tip, leaves, plumule, radicle, cotyledon and embryo to develop a callus from P. vulgaris. The minimum days for callus induction was 10 days in plumule, radicle and embryo explants, while the maximum was 15 days in cotyledon explants with the callus induction percentage of 75%. The largest callus was found to be 2.77 gm in weight and 2.5 cm in diameter in MS medium. Medium with different concentrations of plant growth regulators (PGRs) showed different growth pattern in callus induction. Culture medium with 1.50 mg/l of BAP, 0.50 mg/l of 2, 4-D and 0.10 mg/l of NAA showed the best result in callus induction. Higher concentration of BAP (2.00 mg/l), along with 0.25 mg/l of 2, 4-D was ideal for shoot regeneration and maturation. Shoot induction medium along with 2.00 mg/l of NAA concentrations were found to be best for rooting. It was found that plumule and radicle favor callus induction, however, they are also potent for shoot and root induction. Knowledge gained in this study will be useful in developing a standard protocol for plant regeneration from P. vulgaris explants and will also be useful in creating transgenic line of P. vulgaris.