EFFECT OF VERNALIZATION CONDITIONS ON GROWTH AND DIFFERENTIATION OF CALLUS FROM IMMATURE EMBRYOS AND ON GENERATIVE DEVELOPMENT OF REGENERATED PLANTS OF WINTER-WHEAT

The rate of growth and ability to differentiate of callus, from immatu re embryos of winter wheat var. Grana were determinated. Generative de velopment of regenerants and plants obtained from germinated embryos w as also compared. The vernalization conditions affected the growth rat e and differentiation of calli, but not the generative development of regenerants. These results indicated that, in contrast to immature emb ryo, the callus tissue appeared to be resistant to vernalization treat ment, although the requirements for vernalization of regenerants obtai ned via callus are limited. The ability of winter wheat for generative development may become fully repressed during germination of immature embryo. The obtained data support the hypothesis that this phenomenon results from the replacement of germination of embryos by the another type of development i.e. induction of callus tissue and regeneration of new plants on the way of embryo- or organogenesis. The process of f ormation of undifferentiated callus tissue seems to be connected with only partial blockage of the genes involved in generative development of winter wheat plants.