In the last decade genomics research--the sequencing, identification, and analysis of total the DNA code for each organism--has made huge strides in unraveling the genetic mechanisms behind many physical traits. With plants, this knowledge has provided tools for more precise and complex genetic manipulation to eliminate unwanted characteristics and introduce desirable traits.
Of course, genomics has enabled genetic engineering to make precise changes to an organism's DNA and introduce new, and sometimes foreign, genes to generate strains with completely novel traits, such as plants with herbicide or disease resistance. However, genomics has also significantly impacted standard breeding approaches by enabling selection based on the presence or absence of specific gene sequences in the plants. This molecular breeding approach is rapidly replacing traditional breeding which focuses on selecting specific observable traits in plant variants.
Unlike herbicide resistance, drought tolerance is not a simple trait to define. Many factors control how resilient a plant is to low water conditions, which means many traits, each usually produced by multiple genes, can be manipulated to affect this characteristic. Reflecting the advances made possible by genomic research in both genetic engineering and molecular breeding technologies, both of these approaches were used to successfully develop the three drought resistant corn varieties. Monsanto developed its drought resistant corn using genetic engineering to insert a protective bacterial gene, whereas Syngenta and Pioneer used molecular breeding approaches to bring together genes that produce corn plants with a particular hearty response to low water situations.
To read more about how these strains were developed and the potential for further improvement of drought resistant and other environmental growing stresses, check out the recently posted article, "Breeding Versus Engineering to Make Drought Tolerant Corn" in the GMO secton.