Organelle Segregation in Somatic Cybrid and Hybrid Plants and Progenies Derived from Nicotiana Protoplast Fusion

Abstract

Studies on protoplast fusion which resulted in whole plants were reviewed by Thomas et al. (1979) and Vasil et al. (1979). The main purpose of these studies, and of the more recent ones (e.g., Dudits et al. 1979, 1980; Gleba and Hoffmann 1979; Krumbiegel and Schieder 1974; Melchers et al. 1978; Menczel et al. 1978; Power et al. 1979; Wullems et al. 1980) was merely to obtain intraspecific, interspecific — or intergeneric somatic hybrid plants rather than to follow the genetics of the nuclear and plastome controlled traits in the sexual or androgenic progeny of these hybrids. The approach in the present investigation as well as in our previous studies (Zelcer et al. 1978; Aviv and Galun 1979; Galun and Aviv 1979; Aviv et al. 1980) was to focus on cytoplasmic inheritance and organelle segregation in the hybrids and cybrids resulting from the fusion product and to follow this segregation further in their respective progenies. The rational for this approach was detailed previously (Galun and Aviv 1979) and will be stated here briefly. In most angiosperms organelle inheritance is strictly or predominantly uniparental with Pelargonium and Oenothera being notable exceptions (see Galun 1980 — for details and references). Hence, sexual hybridization between plants which differ in both nuclear and plastome genes will result in segregation of nuclear — but not of plastome genes. On the other hand, in somatic hybrids both nuclear and plastome genes should undergo segregation. Moreover, if the nucleus of one of the fusion partners will be arrested in respect to karyokinensis — only organelle segregation is expected.