Author
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Reed, Sandra |
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Submitted to: Plant Tissue Culture and Development
Publication Type: Book / Chapter Publication Acceptance Date: 5/15/2003 Publication Date: 2/3/2004 Citation: Reed, S. Embryo Rescue. Plant Development and Biotechnology, R.N. Trigiano and D.J. Gray (eds), CRC Press. 2005. pp:235-239. Interpretive Summary: Embryo rescue techniques are among the oldest and most successful in vitro, or tissue culture, procedures used with plant species. Embryo rescue refers to number of techniques that promote the development of an immature or weak embryo into a viable plant. These procedures are often used for producing plants from hybridizations that normally produce inviable seed. This chapter reviews the different types of embryo rescue procedures, along with factors that contribute to their success. Embryo culture, in which embryos are excised and placed directly onto culture media, is the most widely used embryo rescue procedure. Since small embryos are very difficult to excise without damage, entire ovules or ovaries are sometimes placed into culture. Ovule and ovary culture are commonly used for small-seeded species or very young embryos. For all embryo rescue procedures, the probability of success increases with maturity of the embryos; however, cultures must be initiated before embryos die. The type of medium needed for rescuing embryos is strongly dependent on the stage of embryo development. Young embryos require a complex medium with high sucrose concentrations, while more mature embryos can usually develop on a simple medium with low levels of sucrose. Embryo rescue has been used to produce many otherwise incompatible interspecific and intergeneric hybrids, which have in turn been used in plant breeding programs. Continued investigations into nutritional requirements of young embryos, along with modifications of existing embryo rescue techniques, should led to successful application of this highly valuable in vitro procedure to additional crop species. Technical Abstract: The term plant embryo rescue refers to a number of in vitro techniques whose purpose is to promote the development of an immature or weak embryo into a viable plant. Embryo rescue has been widely used for producing plants from hybridizations in which failure of endosperm to properly develop causes embryo abortion. Such hybridizations often result in the production of inviable seeds. In embryo rescue procedures, the artificial nutrient medium serves as a substitute for the endosperm thereby allowing the embryo to continue its development. Embryo culture, in which embryos are excised and placed directly onto culture media, is the most widely used embryo rescue procedure. However, since small embryos are very difficult to excise without damage, entire ovules or ovaries are sometimes placed into culture. Ovule and ovary culture are commonly used for small-seeded species or very young embryos. For all embryo rescue procedures, the probability of success increases with maturity of the embryos; however, cultures must be initiated before embryos abort. The type of medium needed for rescuing embryos is strongly dependent on the stage of embryo development. Young embryos require a complex medium with high sucrose concentrations, while more mature embryos can usually develop on a simple medium with low levels of sucrose. Embryo rescue techniques are among the oldest and most successful in vitro procedures. They have been successful in producing many otherwise incompatible interspecific and intergeneric hybrids. Continued investigations into nutritional requirements of young embryos, along with modifications of existing embryo rescue techniques, should led to successful application of this highly valuable in vitro procedure to additional crop species. |
