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Corn+Soybean Digest

Breeding New Hybrids Still Takes Time

Since John Dudley began his career, plant breeders have slashed the time it takes for desirable traits to become part of farmers' seed-corn selections.

Whether the process can be shortened further is anyone's guess, and whether farmers will be able to afford the results of further shortening is even less clear.

"Theoretically, using biotech methods like cloning and genetic markers can give us material that will address a particular concern in as little as two years," says Dudley, a University of Illinois plant geneticist.

That's in theory. The reality is that it often takes much longer than two years for new genes to reach farmers' fields.

Although biotechnology can shave years off the process of genetic transformation, it remains up to 40 times more costly than traditional backcrossing. So seed companies have tended to reserve biotechnology for genes for which they can charge higher prices, such as those for herbicide tolerance. The traits deemed necessary but less profitable still tend to be transformed via traditional breeding methods.

Once the gene is obtained, regardless of how it's obtained, it must be incorporated into company lines. The resulting hybrids then must be field tested and their seed supply increased before they can be offered to farmers, says Dudley.

According to Greg Parker, plant technology manager for Golden Harvest Seeds, it typically takes just under three years for the company to bring a trait to yield trials from the time it gets the genetic material. That's assuming 3.6 generations per year in the company's Puerto Rican winter breeding program.

It's also assuming that the company only has to go through five backcrosses to get the desired gene into its corn line. Each additional backcross adds about 100 days to the process.

"Five may be slightly optimistic," says Parker. "There is no magic number of times you have to go through the process."

All too often, new genes interfere with existing ones.

"That's true of traditional breeding and it's going to be true with cloned genes as well," says Dudley.

The difficulty in developing corn hybrids, as with any crop, arises because genes aren't typically entities unto themselves. They are part of an entire system of DNA.

Add to this the fact that companies tend to deal with many inbred lines and traits simultaneously in developing a hybrid and you begin to see how the chances for delays and failures can mount.

What's more, after a company incorporates a promising gene into a line it must put the line through the process of self-pollination to ensure the gene will remain true. Only after this process, which takes as much as a year, can a company begin to make hybrid seed and subsequently run yield trials.

Yield, after all, is the bottom line.

"No matter how promising a new gene might be, you can't afford to take too big of a yield penalty," reminds Dudley.

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