Biologists use synthetic biology to reprogram plant responses

Water loss was minimized by genetically modifying plant receptors

It could be the coming out party for synthetic biology in agriculture.

A biologist at University of California Riverside has developed a technique to reprogram plants so they are more tolerant of drought.

Plants that lack water naturally produce abscisic acid (ABA), which restricts plant growth and minimizes water consumption. Scientists have considered spraying plants with ABA to help them combat drought.

However, the chemical is expensive to manufacture and sensitive to light. Other researchers are studying synthetic ABA to promote drought tolerance.

Plant biologist Sean Cutler and his U of C Riverside colleagues took a different approach. They used synthetic biology to alter a tomato plant and arabidopsis, a model plant related to canola and mustard commonly used in biology. The scientists re-engineered the plants’ ABA receptors so that they would be activated by a chemical called mandipropamid, which is used to control late blight in fruit and vegetable crops.

The plants switched on the ABA biological pathway when sprayed with mandipropamid in the lab, which caused the plants to close the guard cells on leaves, called stomata, to minimize water loss.

“We successfully repurposed an agrochemical for a new application by genetically engineering a plant receptor, something that has not been done before,” Cutler said in a statement.

The journal Nature published Cutler’s study in early February.

John Passioura, a scientist with the Commonwealth Scientific and Industrial Research Organization in Australia, told that he’s skeptical about the approach.

He said closing the stomata could interfere with plants’ ability to transpire and cool, which could “cook” the leaves.

Cutler said re-engineering a plant’s response to a particular chemical is much bigger than drought tolerance.

“Using synthetic biology … we took something that already works in the real world and reprogrammed the plant so that the chemical could control water use,” he said. “We anticipate that this strategy of reprogramming plant responses … will allow other agrochemicals to control other useful traits, such as disease resistance or growth rates.”

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