Three researchers affiliated with the Umeå Plant Science Centre have found a key signal to avoid cell death in plants under stress.
Today's plants are not genetically prepared to survive extreme heat and long periods of drought. For example, during the hot summer of 2018, millions of trees died in Sweden alone due to drought, points out Olivier Keech, leader of the project.
This is about genetically programmed leaf senescence (when a leaf turns yellow), which allows the plant to recycle molecules from aging and damaged leaves. Before a leaf dies, the plant recycles nutrients, such as nitrogen, which are transported to other parts of the plant.
To increase the plant's ability to recover when the drought ends, it is important to keep aging leaves alive long enough to transport nutrients to the rest of the plant. Otherwise, in prolonged drought, leaf cells may pass the point where recovery is no longer possible.
As a signal
The researchers have shown that when the amino acid arginine accumulates in the cell's cytosol, that is, the fluid found in the cell, it has a positive signalling effect against cell death.
With high levels of arginine, it is still possible for the plant to recover. Low arginine levels mean that the cells interpret the recycling of nutrients as complete and the plant then starts the process of leaf death.
By regulating cytosolic arginine using various molecular techniques, it would be possible to control the 'point of no return', that is, the point when cells can no longer recover and die, explains Olivier Keech.
Save plants
It is also the mechanism that could save plants after a stressful period, such as prolonged drought.
With the Umeå researchers' discovery, it would be possible to modify the content of arginine during cell death and thus extend the ability of the cells in the plant to survive the stress.
"If you understand how plants die, you also understand how they can survive. It's incredibly important research, so there are many researchers in the world trying to understand the molecular mechanisms that affect cell death, but they don't have exactly the same research strategy," says Olivier Keech.
