Polyamine levels during the development of zygotic and somatic embryos of Pinus radiata

Changes in the cellular content of three polyamines (putrescine, spermidine and spermine) mere compared at different stages of development in zygotic and somatic embryos of Pinus radiata D. Don. During embryo development, bot h the zygotic and the somatic embryos showed a steady increase in spermidin e content, with either a small decrease or no significant change in putresc ine. This led to a several-fold increase in spermidine/putrescine ratios du ring development of both types of embryos. Cell cultures of plant-forming a nd non-plant-forming lines derived from the same clone and growing on proli feration (maintenance) medium differed significantly in their polyamine lev els. Mature, cotyledonary stage somatic embryos capable of germination and formation of plants could be distinguished by their higher spermidine/putre scine ratios from abnormal cotyledonary stage somatic embryos which were in capable of forming plants.