COMPARISON OF UV-LIGHT, X-RAY AND RESTRICTION ENZYME TREATMENT AS TOOLS IN PRODUCTION OF ASYMMETRIC SOMATIC HYBRIDS BETWEEN BRASSICA-NAPUS AND ARABIDOPSIS-THALIANA

Asymmetric somatic hybrids between Brassica napus (receptor) and Arabi dopsis thaliana (donor) have been produced by three different methods supposed to induce asymmetry. The donor protoplasts were either UV- or X-irradiated, or the mixture of protoplasts was treated with the rest riction enzyme PvuII immediately before fusion. The genome composition of the hybrids was analysed with Southern blot hybridisations using 1 5 different mapped A. thaliana RFLP markers as probes. Both UV- and X- irradiation were found to be efficient treatments for induction of asy mmetry in somatic hybrids in a dose-dependent manner. The addition of a restriction enzyme to the protoplast mixture did not have any effect on the frequency of asymmetric hybrids or on the degree of asymmetry in the hybrids produced. UV- and X-irradiation resulted in higher fert ility in the hybrids? while PvuII treatment did not have any effect on seed set. A significant positive correlation between degree of asymme try in different plants and seed set after selfing was detected.