Efficient plant regeneration from rice protoplasts in general medium

We established an efficient and reproducible procedure for protoplast propagation and fertile plant regeneration of rice (Oryza sativa L.) cultivars Nipponbare and Taipei 309. Selection of scutellum-derived secondary calli, the use of General medium and nurse culture were all found to be critical in the procedure. When 5 basal media (Murashige and Skoog, RY-2, modified R2, Amino Acid and General media) were compared, suspension callus growth rate, protoplast yield and plating efficiency were all about 30% higher in General medium than in the second-best R2 medium. Only one month was required to develop suspension cultures for protoplast isolation using General medium. A plating efficiency as high as 17% and a plant regeneration frequency of 67% were achieved by the improved procedure. Agronomic traits of protoplast- and seed-derived plants were found to be similar.