| Summary: | The role of endogenous auxins for the establishment of bilateral symmetry during embryo development was investigated by using in vitro maturation system of Larix decidua somatic embryos and two different types of auxin polar transport inhibitors, TIBA (2,3,5-triiodobenzoic acid) and NPA (1-N-naphthylphthalamic acid). TIBA at the concentration of 10 - 50 uM influenced the morphology shape of differentiated embryos, but it did not show quantitatively the negative effect on the percent normality and conversion rate. Fifty j.IM TIBA was found toxic to early stage of somatic embryo. NPA showed a different effect compared to TIBA. NPA affected the establishment of bilateral symmetry of the differentiated embryo and at least up to 50 uM was not toxic to early stage of somatic embryos. Ten AM NPA in the maturation medium had been already disturbed the morphology shape of differentiated embryos. Many embryos developed to trumpet shape and at higher concentration, NPA perfectly inhibited the embryo development. At the concentration of 50 1.LM, all embryos developed to cucumber-like types. The differentiated embryos failed to become plantlet. Our results supported the hypothesis that endogenous auxin is transported polarly and plays an important role in the establishing bilateral symmetry during development of embryo.
Keywords: Larix decidua �maturation � NPA � TIBA
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