Better understanding of plant defense systems, and the potential to generate stress-tolerant plants and even new malaria drugs, may all stem from the documentation of a molecular mechanism that plays a significant role in the response of plants to physical injuries, such as cuts. A team of agricultural researchers in Japan, led by Fuminori Takahashi of the RIKEN Plant Science Center in Tsukuba, found that the key protein in the complex mechanism is MPK8, which is fully activated by two signaling pathways working in concert.
The researchers showed that MPK8 is activated while the wounded plant mounts an initial emergency response to an injury. Around the fresh wound, the plant produces reactive oxygen species (ROS), such as hydrogen peroxide. These highly toxic compounds kill any pathogens that could access internal tissues via the wound site. However, since ROS can also harm plant tissue they require close regulation. Takahashi and his team—from RIKEN and three Japanese universities—found that the regulator is MPK8.
In addition to the initial response, the injury stimulates the release of calcium ions and starts a cascade of phosphorylation or phosphate-adding compounds. The compounds involved are called mitogen-activated protein kinases (MAPKs). MPK8 is one of the MAPKs of the model plant Arabidopsis.
Takahashi and his colleagues used Arabidopsis plants to investigate how both signaling and the levels of ROS are regulated after physical injury. Using plants into which they had introduced additional copies of the MPK8 gene, the researchers showed that MPK8 was activated under stress, particularly from physical wounding. MPK8 was strongly activated by MKK3, another MAP kinase from higher up the cascade. But it was also activated by calcium ions, specifically when they were bound to proteins called calmodulins. In addition, the researchers determined that the production of MPK8 was associated with regulation of ROS, lowering its accumulation.
A region of MPK8 known as TDY is known to interact or be phosphorylated with both MKK3 and calcium-bound calmodulins. By inhibiting each of these compounds in turn, the researchers showed that full activation of MPK8 demanded activating both of them at once, bringing the signaling pathways together. Finally, by examining the expression of genes, they found that MPK8 regulates the production of ROS by repressing the gene that stimulates their production (Fig 1).
“We think our findings might eventually lead to designing a drug treatment for malaria infection,” says Takahashi, “because the Plasmodium parasite involved uses the same kind of MAPKs.”
The corresponding author for this highlight is based at the Gene Discovery Research Group, RIKEN Plant Science Center
 Takahashi, F., Mizoguchi, T., Yoshida, R., Ichimura, K. & Shinozaki, K. Calmodulin-dependent activation of MAP kinase for ROS homeostasis in Arabidopsis. Molecular Cell 41, 649–660(2011).
Seeking structure with metagenome sequences
20.01.2017 | DOE/Joint Genome Institute
Snap, Digest, Respire
20.01.2017 | Albert-Ludwigs-Universität Freiburg im Breisgau
An important step towards a completely new experimental access to quantum physics has been made at University of Konstanz. The team of scientists headed by...
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
19.01.2017 | Event News
10.01.2017 | Event News
09.01.2017 | Event News
20.01.2017 | Life Sciences
20.01.2017 | Physics and Astronomy
20.01.2017 | Materials Sciences