Environmentally friendly approaches to genetic engineering

Several environmental problems related to plant genetic engineering may pro hibit advancement of this technology and prevent realization of its full po tential. One such common concern is the demonstrated escape of foreign gene s through other crops or toxicity of transgenic pollen to nontarget insects . The high rates of gene flow from crops to wild relatives (as high as 38% in sunflower and 50% in strawberries) are certainly a serious concern. Mate rnal inheritance of the herbicide resistance gene via chloroplast genetic e ngineering has been shown to be a practical solution to these problems. Ano ther common concern is the suboptimal production of Bacillus thuringiensis (Bt) insecticidal protein or reliance on a single (or similar) B.t. protein in commercial transgenic crops, resulting in B.t. resistance among target pests. Clearly, different insecticidal proteins should be produced in letha l quantities to decrease the development of resistance. Such hyperex-pressi on of a novel B.t. protein in chloroplasts has resulted in 100% mortality o f insects that are up to 40 000-fold resistant to other B.t. proteins. Yet another concern is the presence of antibiotic resistance genes in transgeni c plants that could inactivate oral doses of the antibiotic or be transferr ed to pathogenic microbes in the GI tract or in soil, rendering them resist ant to treatment with such antibiotics. Cotransformation and elimination of antibiotic resistant genes from transgenic plants using transposable eleme nts via bleeding are promising new approaches. Genetic engineering efforts have also addressed vet another concern, i.e., the accumulation and persist ence of plastics in our environment by production of biodegradable plastics . Recent approaches and accomplishments in addressing these environmental c oncerns via chloroplast genetic engineering ale discussed in this review.