The science of how plants record shocks takes on a new dimension
Ancient theories about how plants depend on elevated calcium to respond systemically to injury and other stresses have been given a new perspective.
John Innes Center researchers demonstrated that calcium waves are not a primary response, but a secondary response to a wave of amino acids emitted by a wound.
These findings challenge established thinking about long-range plant signaling molecules and the mechanisms by which information from a stress point is transmitted through living and nonliving plant tissues.
It has been observed for many years that injuries and other traumas result in calcium waves that travel short distances from cell to cell and longer distances from sheet to sheet.
These calcium waves are reminiscent of signals seen in mammalian nerves, but since plants do not contain neurons, the mechanism by which this occurs has been questioned.
New discoveries appearing in Scientists’ progress They indicate that when the cell is injured, it releases a surge of the amino acid glutamate. When this wave travels through plant tissues, it activates calcium channels in the cell membranes through which it passes. This activation appears as a calcium wave but is a negative response, or ‘read’ to the moving glutamate signal.
Previous hypotheses to explain how calcium waves travel through plant cells have involved active mechanisms of calcium signal propagation. These hypotheses relied on signal propagation along the cell membrane, or via a pressure wave in the xylem, but there was no explanation for how the response was transmitted from one cell to another.
Dr. Kristin Faulkner, group lead at the John Innes Center, said: “When models are presented for active proliferation, I wonder how this wave travels from one cell to another. There seemed to be a gap in the theory, and this research reveals a new mechanism showing that the calcium wave is not as seen. “
Dr. Faulkner’s group specializes in studying metadata, the channels or bridges that connect cells, and the team hypothesized that the infection signal would travel from one cell to another via the plasmodesmata. However, using quantitative imaging techniques, data modeling and genetics, they discovered that the moving signal is a wave of glutamate that travels outside of cells, along cell walls.
Glutamate and calcium waves correlate – glutamate triggers a calcium response. You can imagine it by analogy with the hallway. Glutamate rushes into the hall, and when it passes through one of the doors, it opens. Calcium response is the key so far, the assumption was that what was moving down the hallway was hydraulic pressure or a series of pervasive chemical reactions, but our study shows that this is not the case,” said Dr. Faulkner.
The study’s first author, Dr. Annalisa Belandi, said: “We have shown that calcium waves are synchronized with glutamate waves, and their dynamics correspond to diffusion and flux transmission. This research makes us rethink what we know. I hope our research will inspire discussion and allow people to gain a new perspective on the existing data. in this field for a long time.”
Diffusion and massive influx of amino acids mediate calcium waves in plants Scientific progress.
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