The production of fertile, triploid somatic hybrid plants (Nicotiana glutinosa (n) + N. tabacum (2n)) via gametic: somatic protoplast fusion.

The fusion of gametic protoplasts with somatic protoplasts giving rise to gametosomatic hybrid plants was investigated. Gametosomatic hybrid plants were regenerated following the fusion of nitrate reductase deficient (Nr(-)) Nicotiana tabacum Nia-130 leaf mesophyll protoplasts with N. glutinosa tetrad protoplasts. The resulting plants were confirmed as hybrids, based on leaf and floral morphology, chromosome number, leaf esterase and leaf callus peroxidase zymograms and Fraction-1-protein analysis. The five gametosomatic hybrid plants had the expected pentaploid, but functionally triploid chromosome number of 3n=5x=60. The relevance of triploid gametosomatic hybrids in facilitating limited gene transfer, is discussed. The utilisation of tetrads as a generally available source of haploid protoplasts for fusion studies is proposed.