Wageningen UR solves mystery of plant defense
Scientists from Wageningen UR have discovered that RLP-receptors located on the outside of plant cells join forces with other proteins at the same location to warn the plant when a fungus attacks. This answers a question that has haunted plant scientists for years. The findings provide new leads for breeding crops with an improved defense against diseases.
Plants are constantly challenged by pathogens such as fungi and bacteria. They almost always succeed in warding off pathogens by using special receptors, either present at the outside or inside of the plant cell, to identify the pathogen. The receptors located at the outside usually also have a domain that protrudes through the cell membrane into the cell. This is used to warn the cell and stimulate the plant cell to take action. This generally results in a 'programmed cell death', ensuring that the fungus, for example, can no longer enter the cell and absorb nutrients.
Although much is known about the defense system of plants, there are still quite some mysteries to be solved. For some time, for instance, we know about the existence of so-called RLK-receptors. These receptors are located at the cell membrane of the plant cells and have a domain on both the inside and the outside of the cell. Whenever they receive a signal on the outside - from a fungus, for example - the part on the inside of the cell (the kinase) activates the signal to mount a defense response against the invading fungus.
In addition to RLK-receptors there are also RLP-receptors. These are also located at the cell membrane, but they do not have a kinase domain on the inside of the cell to pass on signals. For over twenty years, scientists have been mystified as to how these receptors manage to warn the plant to enable it to protect itself against pathogens.
Scientists have now discovered that a number of RLP-receptors indeed recruit an RLK-receptor, referred to as SOBIR1, in order to warn the cell for fungal attacks. Switching off the gene for this RLK-receptor cause the RLP-receptors to be non-functional.
That discovery provides many opportunities for further studies on this type of defense system, which will make it easier to breed plants that are more resistant to pathogenic microbes, which in turn would lead to a reduced use of pesticides.
Read the entire article here, including an illuminating illustration of the process.
Source: Phys.org