Production of cybrid plants within Brassicaceae by fusing protoplasts and plasmolytically induced cytoplasts

Abstract

This investigation demonstrates that cybrid plants can be produced by mass fusion of plasmolytically induced cytoplasts with protoplasts. Cytoplasts were isolated from etiolated hypocotyls and enriched in a mannitol-Percoll gradient prior to fusion. Fusions were induced by PEG, and fusion products were selected using flow sorting. Of the plants obtained from fusions between protoplasts of Brassica napus and a fraction containing 70% cytoplasts of Brassica oleracea, 57% showed the pattern of B. napus for the three nuclear markers studied. In contrast, protoplast-protoplast fusion between B. napus and B. oleracea gave only 7% plants that exhibited B. napus character for all nuclear markers used. These results strongly indicate that most of the plants from cytoplast-protoplasts fusions showing only B. napus nuclear markers originated from cytoplast-protoplast fusions. Of the plants obtained from fusion between protoplasts of B. napus and a fraction containing 50% cytoplasts of Raphanus sativus, however, only 20% showed B. napus pattern for all nuclear markers studied. One explanation could be that R. sativus cytoplasts are more sensitive to the fusion method and selection treatment. This study demonstrates that it is possible to obtain cybrid plants with organelles from the donor line even without external selection pressure favouring the organelles from the cytoplasts during culture of the cytoplast-protoplast fusion products. © 1991.