Protocol optimization for efficient callus induction and regeneration in three Pakistani rice cultivars.

This study was undertaken to standardize an efficient and effective protocol for callus induction, subsequent growth and regeneration in three Pakistani rice (Oryza sativa L.) varieties viz., GNY-53, Basmati-370 and JP-5. MS and N6 media were used for callus induction. Overall, MS medium was found better for callus induction as compared to N6 medium. The growth regulator 2,4-D with varying concentrations (1-3mg/l) were tested for their callus induction and subsequent growth. GNY-53 (83%) and JP-5 (96.66%) showed maximum callus induction frequency on MS medium supplemented with 3mg/l 2,4-D while Basmati-370 (99%) showed higher callus induction frequency on the same medium supplemented with 1mg/l 2,4-D. The callus growth frequencies for varieties GNY-53 (60%) and Basmati-370 (94.73%) were best achieved on MS medium supplemented with 3mg/l 2,4D while JP-5 (73.68%) showed maximum callus growth frequency on the same medium with 1mg/l 2,4-D concentration. Mean square value for variety, treatment and their interactions were recorded for callus induction and growth on both MS and N6 media at probability level of p≤0.05. The regeneration efficiency of these varieties were tested alone on MS medium fortified with two different combinations of NAA and BAP (1mg/l NAA: 2mg/l BAP and 1mg/l NAA:4mg/l BAP). The two varieties GNY-53 (70.27%) and JP-5 (41.81%) showed maximum plantlets formation frequency on 1:2mg/l combination of NAA and BAP whereas Basmati-370 (43.33%) showed higher plantlets formation frequency on 1:4mg/l combination of NAA and BAP. Mean square value for variety, treatment and their interactions were also recorded for regeneration efficiency at probability level of p≤0.05 which showed that these entire factors significantly affect plantlets formation frequency.