Keywords: callus induction, ethylene, habituated calli, hydroponic culture, regeneration.

Although it is generally accepted that plant in vitro culture response is influenced by the donor genotype, the genetic and molecular bases of this phenomenon are barely known. As a consequence, the optimization of tissue culture protocols is mainly empirically done. Researchers of the IGEAF studied the genetic basis of the in vitro regeneration of various plant species, including the tissue culture response of artificially induced barley mutants. One barley mutant, MC 169, carries a nuclear gene, recently described controlling the root growth in hydroponic cultivation. Under this condition, the roots of MC 169 mutant plants were longer than those of the original wild type line MC 182, a fact that was associated with a reduced ethylene biosynthesis. On the other hand, it is known that ethylene accumulation is inhibitory for in vitro regeneration of several plant species. In this study, we compared the in vitro culture response of mutant MC 169 with that of its mother line MC 182. The data about induction and regeneration of calli as well as those of habituated calli formation demonstrated that mutant MC 169 and its mother line MC 182 show a similar in vitro behaviour.