Chromosome instability in somaclones of a Triticum crassum × Hordeum vulgare hybrid

Immature inflorescence culture and subsequent plant regeneration was practiced for four successive cycles using a Triticum crassum × Hordeum vulgare hybrid cultured on Kao's medium supplemented with 2,4-dichlorophenoxyacetic acid (5 mg/mL). In one line, chromosomal mixoploidy was observed among both mitotic and meiotic cells. Variation in chromosome number of 20 to 98 was observed in mitotic and 14 to 68 among meiocytes in the first cycle regenerants. The range in chromosome number decreased in subsequent regeneration cycles. Fragmented chromosomes were observed at low frequencies in both groups of cells. The high frequency of univalents at meiosis was attributed to possible elimination of chromosomes carrying meiotic pairing control genes.Key words: somaclonal variation, hybrids (intergeneric), tissue culture, chromosomal mixoploidy.