von Arnold Sara, Clapham David
Department of Plant Biology and Forest Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden.
Methods Mol Biol. 2008;427:31-47. doi: 10.1007/978-1-59745-273-1_3.
Somatic embryogenesis, the process in which embryos, similar in morphology to their zygotic counterparts, are induced to develop in culture from somatic cells, is a suitable model system for investigating the regulation of embryo development. Through this process, a large number of embryos at defined stages of development can easily be obtained. Somatic embryogenesis in Norway spruce is comprised of a sequence of steps including initiation, proliferation, early embryo formation, embryo maturation, desiccation and germination. To execute this pathway, a number of critical physical and chemical treatments should be applied with proper timing. Embryogenic cell lines of Norway spruce are initiated from zygotic embryos. The cell lines proliferate as proembryogenic masses (PEMs) in the presence of auxin and cytokinin. Early somatic embryos develop from PEMs after withdrawal of auxin and cytokinin. PEM to somatic embryo transition is a key developmental switch that determines the yield and quality of mature somatic embryos. The embryos develop further, to a stage corresponding to late embryogeny, in the presence of abscisic acid. Some cell lines deviate from normal pattern formation exhibiting developmental arrest at certain stages. These arrested cell lines, together with transgenic lines, are valuable tools for studying embryo development. Particle bombardment is routinely used to produce transgenic plants of Norway spruce.
体细胞胚胎发生是指在培养过程中，诱导体细胞发育出形态与合子胚相似的胚胎的过程，是研究胚胎发育调控的合适模型系统。通过这个过程，可以轻松获得大量处于特定发育阶段的胚胎。挪威云杉的体细胞胚胎发生包括一系列步骤，包括起始、增殖、早期胚胎形成、胚胎成熟、干燥和萌发。要执行这条途径，应在适当的时间应用一些关键的物理和化学处理。挪威云杉的胚性细胞系由合子胚起始。细胞系在生长素和细胞分裂素存在的情况下以原胚性细胞团（PEMs）的形式增殖。去除生长素和细胞分裂素后，早期体细胞胚胎从PEMs发育而来。PEM向体细胞胚胎的转变是一个关键的发育开关，决定了成熟体细胞胚胎的产量和质量。在脱落酸存在的情况下，胚胎进一步发育到与胚胎发育后期相对应的阶段。一些细胞系偏离正常的模式形成，在某些阶段表现出发育停滞。这些停滞的细胞系与转基因系一起，是研究胚胎发育的有价值工具。粒子轰击常用于培育挪威云杉的转基因植株。
