What are some limitations of using recombinant (transgenic) DNA technology?

Question

What are some limitations of using recombinant (transgenic) DNA technology?

Answer 1

First of all, recombinant is not the same as transgenic.  You can have recombinant technology that is not transgenic.  For example, if you want to put an allele from one variety of tomato into another variety, but you don't want to interbreed them because you'll lose the other allelic combinations, you can do that through recombinant technology, but since it's a gene from the same species, it is not transgenic.

But, when you are dealing with transgenic recombination, one of biggest limitations is the actual ability to transfer the gene.  Genes are usually carried by a vector (bacter or virus, for example), so identifying the correct gene, correctly splicing it out without carrying along any unwanted DNA, inserting it into your vector successfully, and then being successful in having the vector deliver the gene into the DNA of your host species can take many, many attempts.

The size of the gene is a big limitation.  Bacteria and viruses can only carry small pieces of DNA.  Also, most traits are not the result of a single gene, but many genes working together.  So, if what you're looking for is to transfer a particular trait, it might not be feasible to reproduce that in the new species given the interactions between genes needed to create it.