Organogenesis and somatic embryogenesis have been widely applied as the two main regeneration pathways in plant tissue culture. However, recalcitrance is still a main restriction in the clonal propagation of many woody species, especially in conifers. They undergo a “phase change” that leads to significant loss of organogenic and embryogenic capacity, thus reducing the responsive tissues or organs to juvenile material, and narrowing the competence window. In this sense, in vitro regeneration of mature conifer trees has been a long-cherished goal in many laboratories worldwide. In this work, apical shoot buds were used as explants for both organogenesis and somatic embryogenesis in order to cloning mature trees of Aleppo pine. Reinvigorated axillary shoots were submitted to somatic embryogenesis induction through the manipulation of culture media, including the use of auxins such as 2,4-D and NAA, cytokinins (BA and kinetin) and phytosulfokine (50, 100 and 200 nM). Although somatic embryos could not be obtained, embryogenic-like tissue was produced followed by the appearance of actively proliferating non-embryogenic calli and differences between treatments were found, especially when phytosulfokine was added to the induction media. Organogenic system produced reinvigorated shoots from both BA treatments tested (22 and 44 µM), from juvenile somatic trees and adult trees, and ex-vitro acclimatized plants were developed.
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Biology and Life Sciences - Biochemistry and Molecular Biology
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