Photo by Claudia Sepulveda, UCR
Parasitic weeds are ruthless freeloaders, stealing nutrients from crops and devastating harvests. But what if growers could trick these invaders into self-destructing? Scientists at University of California, Riverside (UCR) think they’ve found a way to turn the weeds’ own biology against them.
This trick is detailed in the journal Science. At its heart lies a class of hormones called strigolactones — unassuming chemicals that play dual roles. Internally, they help control growth and the plants’ response to stresses like insufficient water. Externally, they do something that is unusual for plant hormones.
“Most of the time, plant hormones do not radiate externally — they aren’t exuded. But these do,” said UCR plant biologist and paper co-author David Nelson. “Plants use strigolactones to attract fungi in the soil that have a beneficial relationship with plant roots.”
Unfortunately for farmers, parasitic weeds have learned to hijack the strigolactone signals, using them as an invitation to invade. Once the weeds sense the presence of strigolactones, they germinate and latch on to a crop’s roots, draining them of essential nutrients.
“These weeds are waiting for a signal to wake up. We can give them that signal at the wrong time — when there’s no food for them — so they sprout and die,” Nelson said. “It’s like flipping their own switch against them, essentially encouraging them to commit suicide.”
To understand strigolactone production, the research team led by Yanran Li, formerly at UCR and now at UC San Diego, developed an innovative system using bacteria and yeast. By engineering E. coli and yeast cells to function like tiny chemical factories, they recreated the biological steps necessary to produce these hormones. This breakthrough allows researchers to study strigolactone synthesis in a controlled environment and potentially produce large amounts of these valuable chemicals.
The researchers also studied the enzymes responsible for producing strigolactones, identifying a metabolic branch point that may have been crucial in the evolution of these hormones from internal regulators to external signals.
“This is a powerful system for investigating plant enzymes,” Nelson said. “It enables us to characterize genes that have never been studied before and manipulate them to see how they affect the type of strigolactones being made.”
There is also interest in strigolactones’ potential role in combating HLB disease, which has devastated Florida’s citrus industry.
Scientists still have questions about whether the weed suicide strategy will work in real-world fields.
Source: UCR
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