Analysis of the plastome and chondriome origin in plants regenerated afterasymmetric Solanum ssp protoplast fusions

Protoplasts from potato cultivars used as recipient parents were fused with irradiated protoplasts from wild Solanum donor species. Regenerated plants were analysed by RAPDs to identify hybrids, Irradiation of donor protoplas ts with ionizing irradiation induced a broad range of donor nuclear DNA eli mination in the asymmetric hybrids. Usage of chloroplast (cp)- and mitochon drial (mt)-specific PCR markers made it possible to trace the different ori gins of the cp genome in seven fusion combinations, as well as the mt genom es in two fusion combinations. Regenerated plants with recipient nucleus an d plastome markers from the donors were found in six of the seven analysed fusion combinations. Protoplast fusion has generated novel mt genome combin ations consisting of different portions of the mt genomes from the fusion p artners. Selection of heterofusion products based on fluorescence markers i s an efficient method to obtain asymmetric Solanum hybrids and cybrids from most fusion combinations. Possible models for cybrid formation are discuss ed.