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Comparison of Traditional and Biotech Breeding Methods

Traditional breeding is less expensive, as it does not involve the sophisticated equipment needed for biotech methods.  However, it is less precise and more time consuming.  According to Dr. Jane E. Henney, M.D., commissioner of the FDA, "[biotechnology] provides much more control over, and precision to, what characteristic breeders give to a new plant.  It also allows the changes to be made much faster than ever before" (Thompson 2000).  

Traditional Breeding Methods

Traditional breeding techniques rely on the plant's own reproductive system(s).  These systems include both sexual and asexual reproduction.  Some species can only reproduce through one system while others may use both.

Sexual Reproduction

The flower is the sexual organ of a plant.  Fertilization begins when pollen arrives on the stigma of the flower.  This initiates the development of a tube which grows through the stylus to the micropyle.  Once the pollen tube reaches the micropyle, the tube nucleus degenerates and the two sperm nuclei enter the embryo sac.

One sperm will combine with the egg to form a zygote while the other will form the endosperm with the two polar nuclei of the embryo sac.  The zygote, or embryo, will develop into a seed.  (Welsh 69-71)

images courtesy of Sexual Reproduction in Angiosperms

When breeding plants through sexual reproduction, natural or artificial pollination systems can be used.  In a natural system two classes of pollination can take place: self-pollination or cross-pollination.  Self-pollination happens when pollen from a plant combines with the stigma of a flower on the same plant.  Cross-pollination occurs when pollen from one plant combines with the stigma of a flower on a separate plant. (Welsh 74)  In an artificial pollination system a breeder crosses the male and female gametes of plants with specific traits in order to produce a new genetic combination (Welsh 82).

Asexual Reproduction

Asexual Reproduction does not require the combination of gametes.  Some common methods of asexual reproduction involve cuttings, like with fruit trees; runners, for strawberries; grafting, with some roses; vegetative cloning through crown division, in the case of legumes and perennial grasses.  A common example of asexual reproduction is the planting of the eye of a potato to produce a new plant. (Welsh 95)

Biotech Breeding Methods

Genetically modified organisms (GMOs) can be produced through a number of methods.  These include agrobacterium mediated gene transfer, electroporation, and gene gun mediated gene transfer.

GMOs can fall into two categories: modified or transgenic.  A modified organism has been genetically engineered to control its production of some protein.  No genetic material from other species is added to the organism.  Transgenic organisms have genetic material from one or multiple other species addition to their native genetics.

 

© Copyright 2002 Department of Biology, Davidson College, Davidson, NC 28035

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