Most simply, once these genes, or bits of DNA tied to the genes (known as markers), have been identified, molecular breeders can quickly target offspring inheriting the genes for further development, cutting breeding time and improving the crop's "genetic gain," the generational improvements made to a crop, like increased height, by human selection.
To little public notice, the world's largest seed companies, such as Monsanto Co., Pioneer Hi-Bred International Inc. and Dow AgroSciences LLC, have used molecular breeding to improve their seed varieties in parallel with genetic engineering. At Monsanto, the practice has become so common that, in a recent paper, the firm said "molecular marker assisted breeding is becoming our conventional breeding process," noting that many of its commercial crops are derived with the process.
A company like Pioneer is well aware of the expense and European resistance to genetically modified, or transgenic, crops. They will exhaust molecular breeding options before turning to GM, said John Soper, Pioneer's soybean research director.
"Both transgenics and the use of markers have risen in priority. ... It's been a very exciting time for us," Soper said. "I still think it's kind of the tip of the iceberg on both of these issues."
Markers are also being used to breed traits from otherwise discarded varieties back into cultivated crops. A well-known breeding technique called backcrossing has become far more potent recently, as markers have allowed scientists to locate rare offspring that retain only the desired -- and now detectable -- genes from orphan crops. Previously in backcrossing, many other genes would also migrate from the orphan plant, reducing yield or taste, to farmers' dismay.
At least one trait added with molecular breeding has already been introduced in Asia and Africa: New varieties of rice that resist flooding damage are now being adopted in India, Bangladesh and Southeast Asia. And corn rich in vitamin A precursors is being targeted for release in Zambia by HarvestPlus.
'Knocked out' crops
Crops made with molecular breeding are not classified as genetically modified, since the first step in their development is pollination -- an important distinction. Yet they would be nearly impossible to create without genetic engineering used to evaluate gene function, said Nora Lapitan, a wheat geneticist at Colorado State University.
Recent innovations have made it easier than ever to "knock out" or silence the expression of selected genes. This gene loss can then, in some rare cases, cause large enough changes to demonstrate a genetic function that can be targeted. These are bedrock trial-and-error experiments, Lapitan said.
"It's really classic," she said.
On its own, gene silencing is also being used to create GM crops. Pioneer used the method for soybeans that produce oil with no trans fats, the type of consumer-focused GM improvement seed companies have long promised but failed to release. (The crop is pending U.S. approval.) Many other applications are arising -- for example, Lapitan's lab discovered that inhibiting one gene can broaden wheat's resistance to the devastating Russian wheat aphid.
Sometime in the near future, it is reasonable to expect that crop genes could be more easily shifted between species -- say, adapting the efficient photosynthesis of corn to rice. But even discounting this future, scientists can now move genes within crop varieties, essentially accelerating a natural process, Cambridge's Baulcombe said. It is an open question whether such modification should be considered equal to introducing bacterial genes.
What is not in question is that these biotech crops will be emerging not just from the United States and Europe, but from the developing world. As an E.U. report this year made clear, much GM innovation should be expected outside of the Western seed firms that have long dominated the field.
India alone has at least 10 domestically developed GM crops in its research pipeline -- including GM versions of cauliflower, eggplant and okra, in addition to staples like rice -- and China has invested heavily in the research. Other countries, like Iran, Brazil, Argentina and Indonesia, are set to introduce GM varieties, though many mimic the pest or herbicide resistance of Western crops.