According to a study by scientists at Scripps Research and the Howard Hughes Medical Institute, a family of proteins that sense mechanical force – and enable our sense of touch and many other important bodily functions – are also essential for the growth of the roots of some plants. (HHMI).
The discovery, published in points to an ancient evolutionary origin for the PIEZO proteins, which until now had been mainly characterized in animals. This advance in basic biology may also lead to new strategies for improving crop yields, the researchers say.
“Our discovery that the PIEZO proteins function as transducers of mechanical forces in plants, as well as in animals, suggests the great importance of these proteins for living organisms on Earth,” says lead author Seyed Ali Reza Mousavi, PhD , postdoctoral research associate in Ardem Patapoutian’s Scripps Research Laboratory, PhD.
“It is remarkable that evolution used the same type of molecule so that we can feel the touch and for the roots of plants to detect the hardness of the soil,” says Patapoutian, professor and president of the Presidential Chair in Neurobiology at Scripps Research and researcher at HHMI.
Patapoutian, the lead author of the study, is credited with discovering the PIEZO proteins about ten years ago – a feat that won him the 2020 Kavli Prize in Neuroscience and many other awards. The discovery led to a host of additional discoveries that shed light on a range of medical conditions, from heart failure to chronic pain.
Feel the physical strength
PIEZO proteins bear little resemblance to other families of biological proteins. In mammals – the only major class of animals in which they have been studied much – they form striking helix-like structures in the outer membranes of cells.
When stretched or squeezed past a threshold, these structures allow charged molecules, called ions, to flow into or out of their host cells.
The two PIEZO proteins in mammals, PIEZO1 and PIEZO2, underlie a wide variety of functions that require this conversion of mechanical force into cellular signals – functions including the sense of touch, the sense of body and limb position that allows balance, a sense of bladder fullness and blood pressure regulation.
Patapoutian’s lab and others have found PIEZO-like proteins, with apparent mechanical sensor functions, in other animals, including Drosophila.
An important role in the plant kingdom
When in the long history of life on Earth have these unique and versatile proteins evolved? To help answer this question, Mousavi and other members of the Patapoutian team examined Arabidopsis thaliana, a pest relative of the mustard plant that is a standard laboratory model for plant biology research. The Arabidopsis genome includes a gene encoding a PIEZO-like protein, which suggests that these proteins also function as mechanosensors in the plant kingdom.
Scientists first looked at the locations on the plant where the protein, PZO1, is made and found it concentrated in the ends of the roots. By deleting the PZO1 gene, they observed that Arabidopsis plants had shorter roots. In a long series of additional experiments, they found that PZO1 in root tip cells responds to mechanical stimuli with ion fluxes – making it a mechanosensor like its mammalian counterparts.
It remains a mystery exactly how PZO1’s mechanical-sensing capabilities help roots grow. But Mousavi, Patapoutian, and colleagues suspect that it helps cells at the root tip detect and adapt to the potentially strong mechanical forces they encounter when the root attempts to penetrate soils – especially longer soils. drier and harder.
“If PZO1 activity increases, it could help plants expand their root systems in dry conditions and have better access to water,” Mousavi says. If that turns out to be the case, boosting PZO1 activity could be one way to increase crop yields under difficult soil conditions, he says.
Mousavi is now attempting to clarify the precise function of PZO1 in Arabidopsis with real life experiments. He also hopes to study the role of PIEZO-like proteins in food crops, especially maize and rice.
The research was supported by the Swiss National Science Foundation (P300PA_164695, P2LAP3_151727), the National Institutes of Health (GM114660, R01HL143297), HHMI and the China Scholarship Council.