Somatic Embryogenesis in Wheat and Barley Calli in vitro Is Determined by the Level of Indoleacetic and Abscisic Acids

The effect of a number of phytohormones (IAA, ABA, and cytokinines) on the induction of in vitro somatic embryogenesis in callus cultures of wheat, cultivar Bashkirskaya 26, barley, cultivar Steptoe, and its ABA-deficient mutant AZ34 has been studied. It was shown that the ability or inability for somatic embryogenesis in callus tissue of both wheat and barley is determined by the IAA : ABA ratio. However, the level of cytokinines was similar in both embryogenic and nonembryogenic calli of each object studied. The analysis of callus tissue of the ABA-deficient mutant AZ34 revealed the stimulating role of ABA not only in the induction of somatic embryogenesis but also in the formation of normal embryos.