Contents - Faperta

Biotechnology, Pest Management, and the Environment: The Future 507
aromatic industry, or confer resistance to insect pests and diseases. Future research on
marker-assisted selection to breed for insect resistance should focus on:
• Developing genetic linkage maps of crops;
• Identifi cation of robust QTLs for use in marker-assisted selection for resistance to
insect pests;
• Improving accuracy and precision of phenotyping for insect resistance;
• Development of cultivars with resistance to insects combining transgenic and
marker-assisted selection; and
• Precise mapping of the QTLs associated with resistance to insects to develop new
paradigms in crop breeding.
Transgenic Crops and the Environment
There are a number of ecological and economic issues that need to be addressed when
considering the development and deployment of transgenic crops for pest management
(NRC, 2000; Sharma and Ortiz, 2000). Deployment of insect-resistant transgenic plants has
raised some concerns about the real or conjectural effects of transgenic plants on nontarget
organisms, including human beings (Miller and Flamm, 1993), and evolution of resistant
strains of insects (Williamson, 1992; Tabashnik, 1994; Shelton et al., 2000). As a result, caution
has given rise to doubt because of lack of adequate information. However, genetically
modifi ed organisms have a better predictability of gene expression than the conventional
breeding methods, and transgenes are not conceptually different than the use of native
genes or organisms modifi ed by conventional technologies (Table 19.3).
One of the risks of growing transgenic plants for pest management is the potential
spread of the transgene beyond the target area (Chevre et al., 1997). Genes from unrelated
sources may change the fi tness and population dynamics of hybrids between native plants
and the wild species. Plant breeding efforts, in general, have tended to decrease rather than
increase the toxic substances, as a result, making the improved varieties more susceptible
to insect pests. However, there is a feeling that genes introduced from outside the range of
sexual compatibility might present new risks to the environment and humans, and will
lead to development of resistance to herbicides in weeds, and to antibiotics. While some of
TABLE 19.3
Comparison of Conventional Breeding and Biotechnological
Approaches for Crop Improvement
Conventional Breeding Genetic Engineering
Uses limited gene pool Unlimited gene pool
Simple skills suffi cient Requires highly technical skills
Gene regulation native Gene regulation modifi ed
Imprecise transfer of genes Precise gene transfer
Integration homologous Gene integration random
Function of genes unknown Known gene function