Many ancient plants weren't pretty, they didn't taste good, and they weren't big - but they could defend themselves.

As food science progressed, numerous plants were genetically optimized for better flavor and yield, but some lost their ability to produce certain defense chemicals, making them vulnerable to attack by insects and pathogens. Swiss scientists are exploring ways to help protect 21st century maize by re-arming it with its ancestral chemical weapons.



Before genetic modification, food was pretty nasty. Link: Ben Hayes on Twitter

The researchers, led by Dr. Ted Turlings of the University of Neuchâtel, Switzerland, found that many varieties of modern maize have lost their ability to produce a chemical called E-β-caryophyllene. This chemical is normally produced by traditional ancestors of modern maize roots when the plant is under attack from invading corn rootworms. The chemical attracts 'friendly' nematode worms from the surrounding soil which, in turn, kill the corn rootworm larvae within a few days.

The scientists used genetic transformation to investigate if restoring E-β-caryophyllene emission would protect maize plants against corn rootworms. After introducing a gene from oregano, the transformed maize plants released E- β-caryophyllene constantly. As a result, these plants attracted more nematodes and suffered less damage from an infestation of Western Corn Rootworms.

"Plant defenses can be direct, such as the production of toxins, or indirect, using volatile substances that attract the natural enemies of the herbivores" says Turlings. One of the types of toxins that maize plants produce against their enemies is a class of chemicals called benzoxazinoids. These protect maize against a range of insects, bacteria and fungi pests, yet some species have developed resistance against these toxins and may even exploit them to identify the most nutritious plant tissues.

These results show how knowledge of natural plant defenses can be practically applied in agricultural systems.

"We are studying the wild ancestor of maize (teosinte) to find out which other chemical defenses may have been lost during domestication of maize," Turlings added. "These lost defenses might then be reintroduced into modern cultivars."