Self-help eases stressed out plants

IOWA STATE (US) — Plants are able to tolerate stress because of a built-in alarm system. In the wild, the move is a survival tactic, but for agricultural crops, the self-defense move is counterproductive, reducing yield.

Adverse environmental conditions, including drought, flood, and heat are crop yield’s biggest enemy, even more so that pests and disease, says Stephen Howell, professor of genetics, development, and cell biology at Iowa State University.

“These are environmental stresses that the farmers can’t control.They are acts of nature. And now seed companies are interested in trying to equip plants with the ability to tolerate stress.”

Details of the research are published in the journal Proceedings of the National Academy of Sciences.

Plant cells produce proteins and ship them to different parts of the cell, where they move through the endoplasmic reticulum (ER) and, under normal conditions, are folded into their normal, healthy three-dimensional structures as they are produced.

But when a plant is under stress, its cells produce poorly folded or unfolded proteins. A built-in, quality-control system in the ER, senses the problem, and sets off an alarm in the cell. In response to the alarm, another protein (IRE1) cuts apart an important RNA molecule, but then splices it back together to create a different sequence.

This cut-and-splice event activates a cascade of stress response genes whose products bring about internal defensive measures that help the plant survive.

“Responses that are activated under stress conditions actually inhibit the growth of plants,” Howell says. “This allows them to conserve their energy to survive the stress conditions.”

But “you don’t want crop plants to [stop growing],” Howell says. “You want them to continue to grow and produce even though they are under stress.”

The next step, Howell says, may be to silence the alarm system.

“What may be important is to disable some of these stress responses.That may make the plant be more productive under stress conditions.”

Researchers from the University of Guelph, Canada; and Fudan University, China contributed to the study.

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Natural responses that are activated under stress conditions actually inhibit the growth of plants, allowing them to conserve energy to survive. (Credit: iStockphoto)