Different diploid chromosome numbers have been reported for the tufted deer Elaphodus cephalophus (female, 2n = 46/47; male, 2n = 47/48) in earlier reports. In the present study, chromosomal analysis of seven tufted deer (5♂, 2♀) revealed that the karyotype of these animals contains 48 chromosomes, including a pair of large heteromorphic chromosomes in the male. C-banding revealed these chromosomes to be very rich in constitutive heterochromatin. Chromosome banding and PCR of sex chromosome-linked genes (SRY, ZFX, ZFY) performed on DOP-PCR products of single microdissected X and Y chromosomes confirmed that the large telocentric chromosome without secondary constriction is the X chromosome whereas the subtelocentric chromosome is the Y. The increased size of both, the X and Y chromosome, appears to be at least partially attributable to the presence of substantial amounts of heterochromatin.

By using the protoplast fusion technique, we have obtained 44 regenerated plants, phenotypically different and distinct from their parents, among which we have identified a fertile symmetric somatic hybrid, designated as TG-32, between N. tabacum var. Gexin No.1 and N. glauca. The morphology, fertility, chromosome number and nuclear constitution of the somatic hybrid have been studied in detail. Unlike other asymmetric interspecific somatic hybrids, the chromosome number of the symmetric somatic hybrid is 72, equal to the sum of chromosomes of both parents. The TG-32 plant has flowers similar to those of N. tabacum, but with petals similar to those of N. glauca. Interestingly the offspring of TG-32 vary in seed production ability with temperature, and produce more seeds under a relatively low temperature. Two SCAR markers were used to evaluate genetic variability and structure. The hybrid amplified the expected fragment, but the parents showed only one of two markers. This experimental result supports the hypothesis of the co-existence of two parental genomes in the somatic hybrid.