© 2004 Heron Publishing—Victoria, Canada
Variation in transcript abundance during somatic embryogenesis in gymnosperms
Claudio Stasolla (1, 2), Peter V. Bozhkov (3), Tzu-Ming Chu (4), Leonel van Zyl (5), Ulrika Egertsdotter (6), Maria F. Suarez (3), Deborah Craig (5), Russ D. Wolfinger (4), Sara von Arnold (3) and Ronald R. Sederoff (5)
1. Department of Plant Science, University of Manitoba, Winnipeg, MB R3T 2N2, Canada / 2. Corresponding author (stasolla@ms.umanitoba.ca) / 3. Department of Plant Biology and Forest Genetics, Uppsala Genetic Center, Swedish University of Agricultural Sciences, Box
7080, S-75007, 3 Uppsala, Sweden / 4. SAS Institute Inc., Cary, NC 27513, USA / 5. Forest Biotechnology Group, Department of Forestry, North Carolina State University, Raleigh, NC 27695-7247, USA / 6. Institute of Paper Science and Technology, 500 10th Street NW, Atlanta, GA 30318, USA / Received January 5, 2004; accepted March 13, 2004; published online August 2, 2004
Summary
Somatic embryogenesis of Norway spruce (Picea abies L.) is a versatile model system to study molecular mechanisms regulating embryo development because it proceeds through defined
developmental stages corresponding to specific culture treatments. Normal embryonic development involves early differentiation
of proembryogenic masses (PEMs) into somatic embryos, followed by early and late embryogeny leading to the formation of mature
cotyledonary embryos. In some cell lines there is a developmental arrest at the PEM–somatic embryo transition. To learn more
about the molecular mechanisms regulating embryogenesis, we compared the transcript profiles of two normal lines and one developmentally
arrested line. Ribonucleic acid, extracted from these cell lines at successive developmental stages, was analyzed on DNA microarrays
containing 2178 expressed sequence tags (ESTs) (corresponding to 2110 unique cDNAs) from loblolly pine (Pinus taeda L.). Hybridization between spruce and pine species on microarrays has been shown to be effective (van Zyl et al. 2002, Stasolla
et al. 2003). In contrast to the developmentally arrested line, the early phases of normal embryo development are characterized
by a precise pattern of gene expression, i.e., repression followed by induction. Comparison of transcript levels between successive
stages of embryogenesis allowed us to identify several genes that showed unique expression responses during normal development.
Several of these genes encode proteins involved in detoxification processes, methionine synthesis and utilization, and carbohydrate
metabolism. The potential role of these genes in embryo development is discussed.
Keywords:
embryo development, gene expression, hybridization, microarray, Picea abies, Pinus taeda.
