ANALYSIS OF CORRELATION BETWEEN NUCLEAR-DNA CONTENT, CHROMOSOME-NUMBER, AND FLOWERING CAPACITY OF ASYMMETRIC SOMATIC HYBRIDS OF DIPLOID SOLANUM BREVIDENS AND (DI)HAPLOID SOLANUM-TUBEROSUM

Selected stable standard Solanum genotypes and two populations of asymmetric somatic hybrids between Solanum brevidens (2n=2x=24) and dihaploid S. tuberosum (2n=2x=24) were analyzed to test the resolution of flow cytometric determination of nuclear DNA content (2C value) in terms of a loss or gain of chromosomes, and to analyze the correlation between the 2C value and the chromosome number. Correlation was high within the standard genotypes (r=0.99, P<0.001). However, the correlation was low within the two populations of somatic hybrids (r=0.54 and 0.65, 0.01<P<0.05). Highly chimeric hybrids were readily detected by flow cytometry, whereas microscopic chromosome observations failed to detect them. Data were analyzed regarding their potential usefulness in predicting the flowering capacity. The 2C values deviating from those of the euploid standard genotypes were highly associated with abnormal morphology and lack of flowering. Flowering capacity did not correlate with chromosome number. These results suggest that flow cytometry can be utilized for initial selection of somatic hybrids.