The Influence of Auxin and Cytokinin on Proliferation and Morphology of Somatic Embryos of Picea abies (L.) Karst

Abstract

Embryogenic cell-lines of Picea abies were initiated from mature zygotic embryos and cultured on medium containing 2,4-D and BA The cell-lines were categorized into two main groups (solar/polar and undeveloped embryos), based on the morphology of the somatic embryos and their ability to go through a maturation process when treated with ABA The cell-lines were transferred to media containing (1) 2,4-D and BA, (2) only BA, (3) only 2,4-D or (4) no growth regulators When cultured on a medium containing both 2,4-D and BA new somatic embryos were continually formed In contrast, when they were cultured without one or both of the growth regulators no new somatic embryos were formed Solar/polar and undeveloped embryos responded in the same way On a medium containing only BA the somatic embryos already present increased in size and developed an extremely large embryonic region On a medium containing only 2,4-D the embryos already present became disorganized into loose aggregates When transferred from a medium containing both 2,4-D and BA to one containing ABA, mature somatic embryos developed from the solar/polar type but not from the undeveloped type The ability of the solar/polar somatic embryos to go through a maturation process decreased when they were precultured on a medium lacking auxin and was lost when they were precultured on medium lacking cytokinin The cell-lines containing undeveloped somatic embryos produced mature somatic embryos in one cell-line out of three that had been cultured on the medium containing only BA