FERTILE SOMATIC HYBRIDS BETWEEN BRASSICA-NAPUS AND ARABIDOPSIS-THALIANA

Fertile somatic hybrids between Brassica napus and Arabidopsis thaliana were produced by protoplast fusion and enriched by flow sorting. Isoenzyme analysis and hybridization of repetitive DNA sequences from the two parental species to total DNA from the hybrids were used to verify hybrid characteristics of the nuclear genomes. Of 29 shoots, each from a different callus, 25 had a hybrid pattern for at least one of the markers investigated. Analysis of chromosome number revealed that 11 out of 18 hybrids had the sum of the two parental chromosome numbers. Organelle analysis of 18 hybrids showed that ten hybrids had mitochondrial (mt) restriction patterns identical to those of B. napus, while eight displayed a rearranged mtDNA restriction fragment pattern. B. napus chloroplasts (cp) were favoured in the hybrids, and out of 21 analysed hybrids only one plant had A. thaliana cp. Most of the hybrids had intermediate morphological features compared with those of the parental species and 14 out of the 19 tested hybrids were female fertile and set seed after backcrossing to B. napus. Of the female-fertile hybrids, two were also self-fertile.