Interspecific somatic hybridization in Nicotiana: I. Transfer of partial genome from N. undulata into N. tabacum by protoplast fusion
Liu-Bao, X.-Hang; He-Mengyuan; Xing-Miao; Tao-Wenjing; Hao-Shui
Acta Genetica Sinica 22(6): 463-469
Mesophyll protoplasts of Nicotiana tabacum and callus protoplasts of N. undulata were chemically fused by the "donor-recipient" fusion system (irradiating the donor parental protoplasts with high dose X or gamma rays prior to fusion with protoplast of recipient parent). Cytological observation on 5 hybrid cell lines revealed that 2 of them were probably multi-cell fusion products with mean chromosome numbers 167.2 and 198.4 respectively. While the other 3 cell lines were binary fusion products with mean chromosome numbers 54.3, 70.6 and 62.8 respectively. A characteristic of these 5 hybrid cell lines was the uniquity of chromosome aberrations in all the metaphase cells examined, although the amount of aberrant chromosomes varied greatly among the cell lines. MDH and esterase isozyme analysis of leaf material from regenerants of the 5 hybrid cell lines showed that they were all asymmetric nuclear hybrids with only partial genome from the donor parent N. undulata. Ribosomal DNA analysis indicated that at least some chromosomes (such as satellite chromosome) of the recipient parent might also be eliminated. The existence of an unique fragment in 2 of the 4 hybrids suggested that intermolecular rDNA recombination between the two parents had occurred. Morphology of regenerants from the 2 multi-cell fusion products were abnormal and with difficulty to regenerate roots. While plants regenerated from the other three hybrid cell lines were morphologically similar to the recipient parent N. tabacum and have been transferred to soil. Cytological observation on root-tip cells from these plants showed that they had chromosome numbers from 51 to 66, indicating the high asymmetric nature of these nuclear somatic hybrids.