GPC Members Login
If you have any problems or have forgotten your login please contact [email protected]

Animals' mitochondria defenses discovered in plants

Mitochondria are cell organelles that play critical roles in maintaining the cell's health, or homeostasis. One way that mitochondria do this is by harvesting energy though oxidative phosphorylation, where various enzymes in the mitochondria release energy to produce the molecule ATP, the cell's "energy currency" that can be used in other processes. This is why mitochondria are often described as the cell's "powerhouse."

Most of the mitochondrial proteins are encoded by the DNA in the cell's nucleus. However, mitochondria also contain a little of their own DNA, which encodes some of their proteins as well. Because of this double origin, mitochondria are prone to proteotoxic stress: various factors that damage the production, folding, and 3D structure of mitochondrial proteins, thus affecting their function.

Mitochondria maintain the health of their proteins (or "proteostasis") through an intricate quality-control network of chaperone proteins and protease enzymes. One such example is the mitochondrial unfolded protein response (UPRmt), which describes a sequence of repairing events triggered when a mitochondrial protein becomes unfolded or misfolded, and chaperone proteins are unable to handle it.

The UPRmt essentially synchronizes a number of mitochondrial and nuclear events to ensure mitochondrial proteostasis, and is known to play key roles in metabolism and aging in mammalian cells. However, scientists have not known if it also exists in plants.

Now, Johan Auwerx and postdoctoral fellow Xu Wang in Auwerx's lab at Ecole Polytechnique Fédérale de Lausanne (EPFL) have published a study showing for the first time that the UPRmt occurs in plants as well in response to proteotoxic stress. The scientists studied a small Eurasian plant Arabidopsis thaliana, which has been used as a model organism for studying genetics, evolution, and plant development since the early 1900's.

The researchers used doxycycline, an antibiotic that blocks gene translation in mitochondria to induce proteotoxic stress to the plant's mitochondria, and found that it activated a plant-specific UPRmt and delayed the plant cells growth as well as its biological aging (senescence). This matched previous studies reporting that UPRmt increases the lifespan of worms (C. elegans) and flies (Drosophila melanogaster).

In searching the biological signals underlie the mito-nuclear communication in the UPRmt, the researchers found a systemic hormonal response in the plant cell. The plant hormones (phytohormones) activate a signal from the nucleus to the mitochondrion to repair the stress.

"We found that plant hormone signaling is an essential mediator that regulates mitochondrial proteostasis in plants," says Johan Auwerx. "In addition, our data not only highlight the universal nature of key features of mitonuclear stress signaling pathways, such as the conserved UPRmt, but also indicate specific effectors and transcriptional circuits that are divergent between the plant and animal kingdoms."

Read the paper: Systems Phytohormone Responses to Mitochondrial Proteotoxic Stress.

Article source: Ecole Polytechnique Fédérale de Lausanne.

Image credit: J. Auwerx/EPFL


Climate change risk for half of plant and animal species in biodiversity hotspots

Up to half of plant and animal species in the world's most naturally rich areas, such as the Amazon and the Galapagos, could face local extinction by the turn of the century due to climate change if carbon emissions continue to rise unchecked.

Flood, drought and disease tolerant -- one gene to rule them all

An international collaboration between researchers at the University of Copenhagen, Nagoya University and the University of Western Australia has resulted in a breakthrough in plant biology. Since 2014, the researchers have worked on identifying the genetic background for the improved flood tolerance observed in rice, wheat and several natural wetland plants. In a New Phytologist, article, the researchers describe the discovery of a single gene that controls the surface properties of rice, rendering the leaves superhydrophobic.

Plants overcome hunger with the aid of autophagy

Researchers at Tohoku University have found that plants activate autophagy in their leaf cells to derive amino acids that are used for survival under energy-starved "hunger" conditions. The findings show that amino acid utilization in plants can be controlled by the manipulation of autophagy.