© 2004 Heron Publishing—Victoria, Canada
High stability of nuclear microsatellite loci during the early stages of somatic embryogenesis in Norway spruce
Andreas Helmersson (1, 2), Sara von Arnold (1), Kornel Burg (3) and Peter V. Bozhkov (1)
1. Department of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, P.O. Box 7080, SE-750 07 Uppsala,
Sweden / 2. Corresponding author (andreas.helmersson@vbsg.slu.se) / 3. ARCSeibertsdorf Research GmbH Biotechnology, A-2444 Seibersdorf, Austria / Received June 6, 2003; accepted May 12, 2004; published online August 2, 2004
Summary
Somatic embryos of Norway spruce (Picea abies (L.) Karst.) differentiate from proembryogenic masses (PEMs), which are subject to autodestruction through programmed cell
death. In PEMs, somatic embryo formation and activation of programmed cell death are interrelated processes. We sought to
determine if activation of programmed cell death in PEMs is caused by genetic aberrations during somatic embryogenesis. Based
on the finding that withdrawal of auxin and cytokinin induces programmed cell death in PEMs, 1-week-old cell suspensions were
cultured in medium either with or without auxin and cytokinin and then transferred to maturation medium containing abscisic
acid. We analyzed the stability of three nuclear simple sequence repeat (SSR) microsatellite markers at successive stages
of somatic embryogenesis in two cell lines. There were no mutations at the SSR loci at any of the successive developmental
stages from PEMs to cotyledonary embryos, irrespective of whether or not the proliferation medium in which cell suspensions
had been cultured contained auxin or cytokinin. The morphologies of plants regenerated from the cultures were similar, although
withdrawal of auxin and cytokinin significantly stimulated the yield of both embryos and plants. We conclude, therefore, that
the high genetic stability of somatic embryos in Norway spruce is unaffected by the induction of programmed cell death caused
by withdrawal of auxin and cytokinin.
Keywords:
genetic stability, Picea abies, proembryogenic mass, programmed cell death, simple sequence repeat microsatellite markers, somatic embryogenesis.
