Optimization for in vitro regeneration in four local cultivars of indica rice

The current investigation was planned and designed for optimizing the concentration of plant growth regulators to generate an efficient in vitro callogenesis and plantlet regeneration in four local cultivars of Indica rice. Effects of six different concentrations of 2,4-D (2,4-dichlorophenoxyacetic acid), kinetin and carbon source, amino acids, and solidifying agents on callus induction were observed using mature seeds as starting material. Two different concentrations of NAA (1-naphthaleneacetic acid) + kinetin and IBA (Indole-3-butyric acid) were used for shoot regeneration and root induction, respectively. The highest frequency (100%) of callus was recorded on the medium containing 2mg/l 2,4-D which was followed by 3 mg/l 2,4-D + 10 mg/l kinetin (95.51%) at the dark condition in cultivar Sadamota. Moreover, MS (Murashige and Skoog) medium supplemented with 2 mg/l 2,4-D, L-proline and sucrose (as carbon source) increased the callus induction frequency. The highest percentages of callus induction were found when both the gelrite and agar were used as solidifying agents. The maximum shoot regeneration (66.44%) and shoot number (4.49) were obtained at 0.50 mg/l NAA + 10 mg/l kinetin in the cultivar, Sadamota. Moreover, the highest root induction and root number were recorded at 0.50 mg/l IBA in Sadamota. Overall, the highest optimum callus induction, shoot regeneration and root formation were obtained at 2 mg/l 2,4-D, 0.50 NAA + 10 mg/l kinetin and 0.50 mg/l IBA, respectively. Sadamota exhibited the best plantlet regeneration followed by Kachamota whereas the lowest was displayed by Dudkalam. This regenerated protocol could be utilized for gene transfer in rice for the development of stress-tolerant and high yielding lines in future.