Contents - Faperta

32 Biotechnological Approaches for Pest Management and Ecological Sustainability
the undesirable trans-fatty acids. Amounts of essential amino acids such as lysine, methionine,
threonine, and tryptophan can be increased to improve the nutritional quality of
cereal grains. Transgenic modifi cations have also been used to alter the ratio of amylose to
amylopectin in starch (McLaren, 1998). Decreasing the amounts of oligosaccharides (such
as raffi nose and stachyose) improves digestibility, and decreases the degree of fl atulence
during digestion. Transgenic technology can also be used to remove antinutritional factors
(Kaufman et al., 1998).
Production of Pharmaceuticals and Vaccines
Microbial production of bioactive chemotherapeutics is a classical fermentation technology,
and these molecules have a wide application in veterinary medicine, agriculture, and human
health. Many of these technologies can now be improved through biotechnological applications,
and open up newer vistas for production of many molecules in other organisms and
plants. Plants and other organisms can also be used as factories for producing enzymes for
industrial applications. Several vaccines can be produced in plants (Anderson, 1996). Vaccines
against infectious diseases of the gastrointestinal tract have been produced in potatoes and
bananas (Moffat, 1995; Thanavala et al., 1995; Artsaenko et al., 1998; Tacker et al., 1998). The
antigen proteins produced by the transgenic plants retain the immunogenic properties upon
purifi cation, which can be used for production of antibodies when injected into mice. Mice
eating the transgenic plants have shown an immune response. Such an immune response
has been demonstrated for cholera toxin B (Arakawa, Chang, and Langridge, 1998).
Anticancer antibodies expressed in rice and wheat could be useful in diagnosis and treatment
of this disease (Stoger et al., 1999). There is also a great potential to increase the yield of
medicines derived from plants (e.g., salicylic acid) through the use of transgenic technology.
Production of Antibodies
The ability of antibodies to interact with their cognate antigens with high specifi city and
affi nity has been exploited in a wide range of applications in immunotherapy and immunodiagnostics.
In recent years, plants have been shown to produce numerous antibody
molecules, ranging from small antigen-binding fragments to large multimeric antibody
complexes. The use of plants as a vehicle for antibody production opens up an inexpensive
method for large-scale production of antibodies for immunotherapy and diagnostic
applications (Owen et al., 1992; Fiedler and Conrad, 1995). A range of different antibody
fragments, including those with affi nity for phytochrome (Owen et al., 1992), abscisic acid
(Artsaenko et al., 1995), fungal cutinase (Schouten et al., 1996), oxazalone (Fiedler and
Conrad, 1995), and tobacco mosaic virus (TMV) coat protein (Zimmerman et al., 1998)
have been stably expressed. One of the benefi ts of producing antibodies in plants is the
potential to exploit their natural storage capabilities. Seeds are suitable for expression and
storage of single chain antibodies (scFvs) (Fiedler and Conrad, 1995). Plants are also a suitable
host for producing functional sIgA molecules (Ma et al., 1995). Rosso et al. (1996)
described the transient expression of a functional scFv directed against salivary secretions
of root-knot nematode, Meloidogyne incognita (Kofoid and White) Chitwood, in tobacco
protoplasts, while Baum et al. (1996) expressed a functional whole antibody specifi c to
stylet secretions of this nematode. This approach can be exploited in the future to express
antibodies directed against specifi c functions of herbivorous arthropods.
Genes that are based on antibody technology can also be exploited for genetic transformation
of crop plants. Single chain antibodies can be used to block the function of