Towards reducing genotype specificity in regeneration protocols after somatic hybridization between cultivated sunflower and wild Helianthus species.

Successful application of somatic hybridization in sunflower breeding is limited by low regeneration percentage from fusion products. The effect of pre-treatment media composition on shoot regeneration from electrofusion products of wild and cultivated sunflower was investigated in this paper, with the aim to determine if there is room for improvement of the existing regeneration protocols in order to make them less genotype-dependent. Protoplasts isolated from hypocotyls of two inbred lines of cultivated sunflower were electrofused with mesophyll protoplasts of H. mollis and H. maximiliani . The regeneration was induced only on calluses that were grown on the media with low auxin and high cytokinin contents during the development of calluses from microcalluses (pre-treatment), with silver nitrate as a medium component. Regeneration from fusion products was induced by treatment with a high concentration of TDZ or 2,4 D for a short period of time.