Abstract:Mesophyll protoplasts of Nicotiana tabacum L. and protoplasts from cell suspension of Lycium barbarum L. were heterofused by electrofusion with a frequency of ca. 4%--5%. One hundred cell lines were selected at random identified by isozyme analysis with peroxidase and superoxide dismatase, and the differences from their parent were found. Results indicated that 9 cell lines expressed enzymatic bands characteristic of both parents. Five of the 9 cell lines were highly morphogenic and regenerated numerous young shoots that manifested morphological traits specific to both parents. However, these shoots never grew up or regenerate roots. Esterase analysis of leaf material from the regenerants of 5 morphogenic hybrid cell lines demonstrated that two of them (NL4 and NL8) expressed an unique hybrid band which were not shown in either parents. Cytological observation on parental and NL4 hybrid cell lines revealed that the somatic chromosome number of NL4 varied from 58 to 80, significantly higher than that of either parents. Ribosomal DNA analysis of NL4 and NL8 showed that NL8 covered all fragments of both parents: NL4 did not have the fragments characteristic of Lyciurn barbarurn L. Both hybrids had new fragments, suggestive of intermolecular recombination of rDNAs of the parents. Four normal plants morphologically similar to tabacco parent were obtained from hybrid cell hne NL4, which survived after being transferred to soil. Cytological analysis of root-tips from one of the plants indicated that it has ca. 58 chromosomes. This paper also discussed the problems on the production frequency and incompatibility of somatic cell hybrid.