Using Biotech to Speed Classical Breeding

Biotechnology, somewhat like the proverbial hare in its contest with the tortoise, raced speedily to bring forth corn transformed with a bacterial protein to resist insects. But now the new science is set to help hasten traditionally slower classical plant breeding to develop insect-resistant corn breeding lines, without the foreign genes.

For example, through 15 years of work, researchers developed corn inbred line Mo47, which is renowned for its ability to resist both first and second generations of the European corn borer. On U.S. farms, European corn borers are responsible for annual damage and control costs exceeding $1 billion.

Recently, Agricultural Research Service (ARS) scientists at Columbia, Mo., and their University of Missouri colleagues, in three years, used fast-paced biotechnological tools to find locations of DNA sequences that confer borer resistance to Mo47. Soon corn geneticists, in a process called marker-assisted selection, may use the information to quickly develop improved insect-resistant corn from diverse genetic resources.

Marker-assisted selection is a way of dealing with the fact that typically, multiple genes govern a single trait of economic importance. These genes’ locations are called quantitative trait loci (QTLs). In DNA marker-assisted selection, researchers conduct DNA tests on corn breeding lines to find out whether they have the most desired QTLs. Lines that do are used for breeding.

ARS geneticist Michael D. McMullen and collegaues in Missouri found, on six chromosomes, nine QTLs associated with Mo47's resistance to first-generation European corn borer leaf feeding damage. The researchers also found seven QTLs for resistance to second-generation borer stalk tunneling damage.

ARS is the chief scientific research agency of the U.S. Department of Agriculture. The ARS scientists are based at the Plant Genetics Research Unit.