LONG-TERM CALLUS-CULTURES OF DIPLOID BARLEY (HORDEUM-VULGARE) .2. EFFECT OF AUXINS ON CHROMOSOMAL STATUS OF CULTURES AND REGENERATION OF PLANTS

Chromosomal abnormalities increased with time on the relatively high concentrations (2.0mg/l or more) of 2,4-D. Prolonged exposures of cell cultures to high concentrations of 2,4-D significantly increased the percent polyploid mitoses and were also associated with increased abnormalities of the spindle apparatus. Cultures maintained in the presence of NAA had a large number of cells with structural alterations of the chromosomes. The best embryogenic callus production (those maintained on 0.1 and 1.0 mg/l 2.4-D) occurred in cultures with least detectable genetic variation. Plants could not be regenerated from cultures that had been on the maintenance media for seven months or more. The loss of regeneration potential was uniform across the concentrations and auxins tested, and only correlated with time. This loss could not be associated directly with detectable genetic variation. © 1990 Kluwer Academic Publishers.