Nurse culture of Japanese radish (Raphanus sativus L.) mesophyll protoplasts

Abstract Mesophyll protoplasts of 11 cultivars of Japanese radish ( Raphanus sativus L.) were cultured. Using protoplasts or cultured cells of different species as nurse, the efficiency and reproducibility of colony formation were improved and protoplasts of all cultivars grew into colonies. Cells of Nicotiana, Brassica, Daucus, Lactuca and Asparagus were effective as nurses, while those of Oryza were not. N. tabacum protoplasts just isolated and those cultured for more than 50 days showed equal effectiveness as nurses. The number of nurse cells correlated with the efficiency of colony formation of the nursed protoplasts: generally highest efficiency was achieved when the numbers of nurse cells and the nursed protoplasts were nearly equal. Although cell division and colony formation were improved by the nurse culture method, viability and cell wall synthesis were unaffected. Conditioned medium showed less promotive effect than nurse culture.