mustard-cousin, Arabidopsis thaliana.
The plant, featuring a relatively small genome, admirably serves the purposes of researchers worldwide.
Tierney wants to learn more about what controls the way root cells take up water and nutrients.
A soil-dwelling bacteria — the same one responsible for crown gall — helps with the heavy lifting.
In the service of human interests, Tierney prompts this micro-engineer to selectively disrupt DNA in the mustard's genome.
By observing those disruptions, Tierney is able to identify, with precision, which genes respond to environmental changes in light, drought and interactions with other organisms, such as insects.
"What we learn in this model system helps us ask the right questions as we look into crop plants that share the same genes," she said.
"We could breed plants that would be more tolerant of marginal environments; breed plants that are able to grow better as our climate changes — because the current crops we have are adapted to the climate that we have."
Traditional breeding methods that pull variety from within the same species of food crop have "plateaued," and will unlikely keep pace with Earth's rapidly changing growing conditions and ballooning human population, Tierney said.
In theory, genetically modified plants would improve humanity's chances. But in most cases, the leap from lab to field remains hypothetical.
Public opposition to GMO crops, coupled with a time-consuming and costly federal approval process, have largely restricted the roll-out of transgenic plants to those with well-heeled backers.
Among the 30-or-so transgenic crops: Feed corn and soybeans, cotton, sugar beets and canola.
With less lavish sponsorship, transgenic "golden" rice was developed about 15 years ago.
It remains unmarketable due to concerns over its inadvertent spread to non-GMO rice, and unforeseen health and environmental impacts.
At the cellular level, the mutation appears to be straightforward.
Two genes inserted into the rice facilitate the grain's content of beta-carotene, a precursor to Vitamin A that normally occurs only in the plant's leaves.
Golden rice has the potential to promptly remedy Vitamin A deficiency in the world's poorest, most poorly nourished communities, Tierney said.
Critics, such as the environmental advocacy group Greenpeace, argue that in the long run, providing a greater diversity of grains, fruits and vegetables, would offer those communities a less risky, time-tested remedy.
A polarized discussion of GMOs plays into the hands of well-funded interest groups at each extreme of the spectrum, Tierney said.
Lost in this shuffle, she added, are useful discussions over how the general public has come to associate GMOs with the agendas of large corporations.
The correlation is understandable. Our highest-profile transgenic crops feature in quarterly earnings of Monsanto, Dupont and other giants.
But the decision to plant a monoculture or clear-cut a hillside, or spay a crop in herbicide can — and should — become decoupled from an association with GMOs, Tierney said.
Just as plausible, she added, are transgenic plants that enhance local food systems and reduce pesticide use.
Avoiding GMO foods
The notion provokes yet another tricky conversation.
Step one is pretty simple, Tierney says: Stay away from high-fructose corn syrup and soybean oil — the most common source of transgenic plants in processed food.
Step two: Restrict your diet to certified organic foods, which are produced without GMOs.
But a closer look shreds any notion of purity.
"There can't be a 'zero tolerance' for GMOs," Tierney said. "It's impossible. For example, in the case of corn, you'd have to test every kernel on every ear — because each of those is an individual pollination event."
Thorough, fool-proof testing, in other words, would not only be prohibitively expensive and time consuming, but would reduce every kernel in that ear of corn to mush.
Tierney offered one glimmer of certainty: A broad swath of scientists, relying on a plethora of peer-reviewed research on pre- and post-GMO health statistics, h