Scientists have discovered a way for remotely regulating a plant’s stomata, which are the holes that allow leaves to control how much CO2 they collect and how much water they let to evaporate.
Each stomatal hole is surrounded by two guard cells. When the guard cells’ internal pressure falls, they slacken and seal the hole. When the pressure rises, the guard cells pull away, causing the hole to expand.
The signaling pathways inside guard cells are complex, making intervention difficult, but the authors of a new study — published Friday in the journal Science Advances — have developed a way to manipulate the stomata using light pulses.
To begin, researchers from Germany’s Julius Maximilian University of Würzburg implanted a light-sensitive protein switch in tobacco plant guard cells – a technique from the area of optogenetics that has previously been utilised in animal cells.
The light-sensitive protein Guillardia theta from the algae species Guillardia theta was utilised to make the switch.
When exposed to light pulses, the protein and its anion channel ACR1 escort chloride out of the guard cells, allowing potassium to exit.
The pressures inside the guard cells drop as a result of the evacuation, and the pore closes within 15 minutes.
“The light pulse is like a remote control for the movement of the stomata,” lead researcher Rainer Hedrich, a professor of biophysics at JMU, said in a press release.
According to Hedrich, the latest findings offer proof of the connection between anion channels and stomatal regulation.
In the future, botanists and crop scientists may be able to engineer plant varieties with more anion channels in their guard cells. This would allow them to more efficiently open and close their pores to protect themselves from heatwaves and prolonged droughts.
“Plant anion channels are activated during stress; this process is dependent on calcium,” Hedrich said. “In a follow up optogenetics project, we want to use calcium-conducting channelrhodopsins to specifically allow calcium to flow into the guard cells through exposure to light and to understand the mechanism of anion channel activation in detail.”
Hedrich suggests their new remote control can be used to conduct a variety of novel plant experiments.
“With it, we can gain new insights into how plants regulate their water consumption and how carbon dioxide fixation and stomatal movements are coupled,” he said.