A procedure for regenerating Japonica and Indica varieties of rice from protoplasts

Fertile rice plants have been regenerated from protoplasts of two japonica rice varieties (Radon and Baldo) using a protocol initially developed for plant regeneration from protoplasts of an indica rice. Embryogenic calli were developed from immature embryos of Radon and Baldo rice on a callus induction medium, and then used to establish cell suspensions. Protoplasts were isolated from the cell suspensions, and cultured on a Millipore filter placed on a Kao/agarose medium that contained cell clusters from suspensions of IR52 or IR45. The protoplasts grew vigorously on Kao medium and developed into embryogenic calli within two to three weeks. Somatic embryo development occurred during a subsequent transfer of the calli to an LS medium for two to three weeks. The calli were then transferred to MS or N6 plant regeneration medium, and within one to three weeks, plants regenerated from 21 to 32% of the Radon calli, and 33 to 35% of the Baldo calli. Based upon these results and the previous success in regenerating an indica variety from protoplasts, this procedure has great promise for regenerating a range of rice varieties, and probably for regeneration of other monocotyledonous plants from protoplasts