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Is Predetermined Cellular Competence Required for Alternative Embryo or Shoot Induction on Sunflower Zygotic Embryos?
Author(s) -
Jeannin Geneviève,
Charrière F.,
Bronner R.,
Hahne G.
Publication year - 1998
Publication title -
botanica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.871
H-Index - 87
eISSN - 1438-8677
pISSN - 0932-8629
DOI - 10.1111/j.1438-8677.1998.tb00709.x
Subject(s) - zygote , explant culture , biology , embryo , somatic embryogenesis , shoot , botany , microbiology and biotechnology , sucrose , somatic cell , embryo culture , sunflower , embryogenesis , genetics , horticulture , biochemistry , in vitro , gene
Somatic embryos and adventitious shoots can be induced simultaneously on immature zygotic embryos of sunflower, their relative distribution on the explant being constant but their relative number depending on the sucrose concentration of the culture medium. We show here that the cells at the origin of both types of structures are competent for either development and express this potential as a function of their position relative to the medium. Two zones, inductive for somatic embryos or adventitious shoots, have been established under the influence of the culture medium. The precision of their localisation is demonstrated by the existence of tissue chimeras which also indicate the presence of diffusible signal(s) responsible for the determination of cellular identity. We have further determined that commitment to the organogenic pathway occurred very rapidly, i.e. within 12 h after the onset of the culture. A synthetic model is presented in which we suggest a possible sequence of key events involved in the morphogenic processes.