During waterlogging or flooding, plants can’t take up enough oxygen that they urgently need for their cellular respiration and energy production. Plants respond to this state of hypoxia with the activation of certain genes that help them cope with the stress. Until now it was unclear how plants are sensing the oxygen concentration. Recent experiments show that under hypoxia a protein that can activate genes, a so-called transcription factor, is released from the cell membrane to accumulate in the nucleus and trigger the expression of stress response genes.
Although plants produce oxygen via photosynthesis, in darkness they rely on external oxygen supply just like humans and animals. If the plants are cut off from oxygen supply, as a result of flooding for example, the energy production in the cells comes to a halt and the plants have to adjust their metabolism to the changed conditions. Hitherto, little was known about the way organisms sense the oxygen concentration of their surroundings. According to new discoveries the key component of this pathway in plants is a protein called RAP2.12, which is capable of binding to certain regions of DNA, thereby triggering the transcription of stress response genes. Scientists observed that plants with an overexpression of RAP2.12 show an enhanced tolerance to submergence and a better recovery after flooding events.
Of special importance seems to be the N-terminus of a protein, so to say the beginning of the amino acid chain. If this amino acid sequence is altered by adding or removing amino acids the plant’s response to low oxygen availability deteriorates. Under normal aerobic conditions RAP2.12 is attached to the cell membrane. When the oxygen level declines, the protein detaches from the membrane and accumulates in the nucleus where it can fulfill its duties as a transcription factor and activate certain genes. As soon as the oxygen availability rises to normal levels RAP2.12 is quickly degraded to stop the transcription of the stress response genes. In plants that express an N-terminally altered RAP2.12 the researchers found the protein to be present in the nucleus even before the oxygen stress started. Under hypoxia the modified protein accumulated in the nucleus but it was not degraded when the oxygen levels rose to normal conditions.
Still, it remained unclear how RAP2.12 sensed the change in oxygen concentration. Scientists of the Max-Planck-Institute of Molecular Plant Physiology together with colleagues from Italy and the Netherlands discovered that the so-called N-end rule comes into play. “According to the N-end rule the first amino acid of a protein determines its life span”, explains group leader Joost van Dongen, “there are stabilizing and destabilizing amino acids”. Cysteine, the first amino acid of RAP2.12 belongs to the group of destabilizers – but only, if oxygen is present. Under hypoxia the life span of RAP2.12 increases, it detaches from the cell membrane and makes its way into the nucleus where it triggers the expression of stress response genes. When the oxygen level inside the cell goes back to normal RAP2.12 is degraded in less than one hour. “Our discovery of RAP2.12 as a central component of the oxygen sensing mechanism in plants opens up interesting possibilities to increase the flooding tolerance in crops” illustrates van Dongen. After all, about ten percent of the arable land worldwide is subject to temporary flooding each year.Contact
Nature, Online publication 23 October, DOI: 10.1038/nature10536
Ursula Ross-Stitt | Max-Planck-Institut
Scientists uncover the role of a protein in production & survival of myelin-forming cells
19.07.2018 | Advanced Science Research Center, GC/CUNY
NYSCF researchers develop novel bioengineering technique for personalized bone grafts
18.07.2018 | New York Stem Cell Foundation
A new manufacturing technique uses a process similar to newspaper printing to form smoother and more flexible metals for making ultrafast electronic devices.
The low-cost process, developed by Purdue University researchers, combines tools already used in industry for manufacturing metals on a large scale, but uses...
For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.
To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...
For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.
Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...
Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.
A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...
Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.
"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....
13.07.2018 | Event News
12.07.2018 | Event News
03.07.2018 | Event News
20.07.2018 | Power and Electrical Engineering
20.07.2018 | Information Technology
20.07.2018 | Materials Sciences