EFFECTS OF CAFFEINE ON SOMATIC EMBRYOGENESIS INDUCTION AND EXPRESSIONIN LEAVES OF A CICHORIUM HYBRID

Caffeine (5 mM), an inhibitor of cell plate formation, is sequentially added during somatic embryogenesis in leaves of a Cichorium hybrid (C . intybus x C. endivia). Somatic embryogenesis is induced in two steps . When caffeine is added during the induction step, the main cytologic al modification consists of an inhibition of the pre-mitotic migration of the reactivated nuclei. When the drug is supplemented during the e xpression step, the same features appear but are less expressed. Norma l somatic embryos and coenocytic structures are observed into the expr ession medium. If caffeine is added during the whole culture, no embry os are observed. Slight variations of alpha and beta tubulins, and an accumulation of actin are detected when medium contains caffeine.