INTRODUCTION OF A GENE FROM FERTILITY RESTORED RADISH (RAPHANUS-SATIVUS) INTO BRASSICA-NAPUS BY FUSION OF X-IRRADIATED PROTOPLASTS FROM A RADISH RESTORER LINE AND IODACETOAMIDE-TREATED PROTOPLASTS FROM A CYTOPLASMIC MALE-STERILE CYBRID OF BRASSICA-NAPUS

To establish a cytoplasmic male-sterile/restored fertility (cms-Rf) sy stem for F-1 seed production in Brassica napus, we transferred a gene from fertillity restored radish to B. napus by protoplast fusion. X-ir radiated protoplasts, isolated from shoots of Raphanus sativus cv Kose na (Rf line), were fused with iodoacetamide-treated protoplasts of a B . napus ems cybrid. Among 300 regenerated plants, six were male-fertil e. The fertile plants were characterized for petal color, chromosome n umber and the percentage of viable pollen grains. Three fertile plants had aneuploid chromosome numbers and white or cream petals, which is a dominant marker in radish. Of these three plants, one which had 2n = 47 chromosomes and white petals was used for further backcrosses. Aft er two backcrosses, chromosome number and petal color became identical to that of B. napus. No female sterility was observed in the BC3 gene rations.