An Updated Overview of Advances in Somatic Embryogenesis in Forest Trees

Somatic embryogenesis has the vast potential to produce plants in their millions, and has now become a routine protocol for many trees. However, the use of SE in a wide range of woody plants is yet to be utilized due to several limitations facing the process, including poor germination of somatic embryos, genotypic influences, a limited number of explants inducing SE, and somaclonal variation. These limitations have hindered the commercialization of SE in a wide range of forest trees. Further research is required at both the biochemical and molecular levels to understand the mechanism of SE, enabling the induction of SE in other recalcitrant woody species. A sharp focus is needed to increase the rate of ESM establishment, improving yield from established ESM, and increasing the germination rate of somatic embryos for commercialization, without which this technology will have very limited scope (Timmis 1998). Automation of somatic-seed production is the ultimate goal of commercial seed industries. The combination of high technology with tissue culture, including computer-aided image analysis, robotics, bioreactors (including temporary immersion systems) somatic-embryo encapsulation, development of appropriate somatic-embryo coating material, etc., require further investment for producing millions of somatic seeds in a short time and to cut down the cost of seed production. The genetic fidelity of somatic seedlings is important for all of this, which can be tested with molecular markers, such as AFLPs or microsatallites. Although several molecular markers are available, a reliable molecular diagnostic kit is still needed for the early detection of genetic variability during plant development.