HomeInternational Rice Research Notesvol. 22 no. 2 (1997)

Callus Induction from Indica Rice Coleoptiles

Y Coll | A Gonzalez | J Alfonso | R Armas | M Pujol



Rice coleoptiles have been used in tissue culture and genetic transformation, but reports on callus induction and subsequent plant regeneration from such explants in indica type varieties are scarce. We obtained significant improvements in callus induction from coleoptiles by testing different explant and culture media conditions. Mature seeds from the Perla rice cultivar were dehulled, sterilized, and the seedlings were grown on solid MS medium in the dark at 27°C. Coleoptiles were aseptically extracted with a scalpel from 3-, 4-, 5-, or 7-d-old seedlings and incubated in N6 medium supplemented with 2 mg 2, 4-D L-1 (N621, unless otherwise stated. In the first attempt for inducing callus from both apical and basal portions from coleoptiles (Fig. 1), apical sections did not render callus regardless of their age in culture. Basal portions from coleoptiles cultivated for 3, 4, or 5 d produced significantly more calli than did those from 7-d-old coleoptiles (Fig. 2a), so in all subsequent experiments only basal portions from 3-d-old rice coleoptiles were used. Figure 1 shows results of culturing coleoptile basal portions in N62 medium with NAA. Adding 0.1 mg NAAL-1 resulted in a significant increase in callus induction over N62 medium containing no NAA. Concentrations of 0.5 or 1 mg NAAL-1 also improved induction as compared with the N62 medium. Effects increasing sucrose concentration were also tested. While 4.5% sucrose increased callus formation very significantly, 6% gave results lower than the control (Fig. 2b). Effects of using 2, 4-D at 3, 4, or 5 mgL-1 were compared with those at 2 mgL-1. Concentrations higher than 2 mgL-1 improved callus induction (Fig. 2b), but no significant differences were found among 3, 4, or 5 mgL-1.