Morphological and cytological characteristics of somatic hybrids of Nicotiana tabacum L-(+) N-megalosiphon Heurk. et Mull.

Somatic hybrid plants of Nicotiana tabacum (bar) (+) Nicotiana megalosiphon (npt II) were recovered after polyethylene glycol (PEG) mediated fusion. H ybrid calluses were selected on the basis of their dual resistance to biala phos and kanamycin or UV inactivation of the donor species (Nicotiana megal osiphon) protoplasts. The hybrid nature of the individual clones obtained w as confirmed by AFLP analysis. An array of plants were recovered including self-fertile hybrid plants with N. tabacum or N. megalosiphon phenotype, se lf-sterile plants with N. tabacum habit, leaf and intermediate flower morph ology, self-sterile plants with N. megalosiphon habit, abnormal leaves and intermediate flowers, and self-sterile plants of N. megalosiphon type with abnormal characters. Viable pollen was observed in hybrid plants from the t hird group. The hybrids possessed a nuclear DNA content near that of the di ploid tobacco or N. megalosiphon, and also near that of the tetraploid geno me size of N. megalosiphon. The results provide evidence for nonpreferentia l loss of one of the parental genomes and spontaneous asymmetrization of hy brid plants. The present study shows that by means of somatic hybridization a great genetic diversity in the hybrid clones can be achieved.