VERTICLE GENE TRANSFER

an microorganisms take up genetic material from plants and integrate it into their genomes? Could this be a way for genes from genetically engineered plants to spread in the environment? Safety research has been looking into these questions for almost twenty years.

Vertical gene transfer: Nature’s system for higher organisms

The transfer of genetic material to offspring, or the inheritance of genes by subsequent generations, is an essential basis of the evolutionary process. The most common form of gene transfer for higher organisms is sexual reproduction. In the case of higher plants, genetic information is passed along to the next generation by pollination. This is called vertical gene transfer.

Horizontal gene transfer: From plants to microorganisms

Horizontal gene transfer The movement of genetic material between unrelated species is known as horizontal gene transfer. This phenomenon is known to occur in bacteria. One way this can happen is the direct incorporation of free DNA by bacterial cells. This direct form of gene transfer, for instance in the soil or in the digestive tract of animals, is the most commonly predicted scenario for the transfer of genetic material from transgenic plants to microorganisms. So far, horizontal gene transfer can only be demonstrated under optimised laboratory conditions. It was shown that horizontal transfer of genes from plants into bacteria occurs extremely infrequently, and it is therefore difficult to detect.

Ongoing safety research is studying transgenic plants to see if horizontal gene transfer to microorganisms is possible, common, or if it would cause any considerable consequences. One example of such a concern is with antibiotic resistance genes that are found in some GM plants. Antibiotic resistance genes are used as marker genes in the development of transgenic plants. They help scientists find out which cells successfully incorporated the gene of interest. GM crops developed with systems for marker gene removal are a very recent devlopment. The maize line LY038 with enhanced lysine content was recently submitted to the EU for authorisation and is free of marker genes. It is hoped that GMOs without marker genes will simplify safety assessments.