CYTOGENETIC VARIATION IN SOMATIC TISSUE-CULTURES AND REGENERATED PLANTS OF BARLEY (HORDEUM-VULGARE L)

Chromosome number of morphogenic and non-morphogenic calli and regener ated plants of barley were determined. Cultures were obtained from two kinds of explants, immature embryos and seedling leaves from three cu ltivars, Ingrid, Dissa and Golden Promise. Callus chromosome analyses were carried out during a 12 month period in a medium containing 2 mg/ l of 2,4-D. Diploid cells were predominant in all cases; although in l eaf-derived cultures tetraploid cells (2n = 4x = 28) showed a tendency to increase as time in culture increased and after more than six mont hs in culture, diploid cells decreased to percentages of almost 70%. A neuploid cells were generally infrequent in all cases. The source of e xplant has been more important than the genotype (cultivar) and the ty pe of callus (morphogenic vs. non-morphogenic) in the chromosomal stab ility of cultures as time increases. From short term cultures, only 1. 85% of the regenerated plants were tetraploid, the remaining were dipl oids. The ability of morphogenic calli to regenerate plants decreased before any significant reduction of diploid cells were observed.