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 asym metric somatic hybrids between Solanum brevidens (2n=2x=24) and dihapl oid S. tuberosum (2n=2x=24) were analyzed to test the resolution of fl ow cytometric determination of nuclear DNA content (2C value) in terms of a loss or gain of chromosomes, and to analyze the correlation betw een the 2C value and the chromosome number. Correlation was high withi n the standard genotypes (r=0.99, P<0.001). However, the correlation w as 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 c ytometry, whereas microscopic chromosome observations failed to detect them. Data were analyzed regarding their potential usefulness in pred icting the flowering capacity. The 2C values deviating from those of t he euploid standard genotypes were highly associated with abnormal mor phology and lack of flowering. Flowering capacity did not correlate wi th chromosome number. These results suggest that flow cytometry can be utilized for initial selection of somatic hybrids.