Revealing Protein Problems In Hybrid Plants

Misfolded proteins may be responsible for decreased survivability in hybrid plants, say researchers in Japan.

AsianScientist (Oct. 31, 2019) – Scientists in Japan have discovered a cellular mechanism that could be targeted to increase the survivability of hybrid plants. They reported their results in the journal Scientific Reports.

Hybrid plants produced by crossing two different types of parents often die under conditions in which both parents would survive. This is known as hybrid lethality. Certain hybrid tobacco plants, for example, thrive at 36 degrees Celsius but die at 28 degrees Celsius, which is the temperature at which both parents would thrive.

A team of researchers at Tokyo University of Agriculture and Technology, Japan, has begun to unravel the molecular mechanisms by which hybrid tobacco plant cells meet their demise, with implications for other hybrid crop plants. The team observed that when hybrid tobacco plant cells are moved to a lower temperature, they undergo a process called programmed cell death more rapidly than the rate at which they can be replenished.

“What induces programmed cell death related to hybrid lethality in plants? This is the problem we set out to better understand,” said Associate Professor Tetsuya Yamada at the Tokyo University of Agriculture and Technology.

Using powerful imaging tools, the researchers found protein aggregates—proteins that are misfolded or otherwise mutated—building up inside the hybrid plant cells.

“We found that programmed cell death is induced in plant cells by the accumulation of protein aggregates resulting from loss of protein homeostasis,” Yamada said.

Protein homeostasis refers to the intricate and fragile balance between the development of new proteins and the death of old proteins in the already delicate cellular ecosystem. The loss of homeostasis may result from an autoimmune response, which is induced after the temperature shift, according to Yamada.

To combat this cellular decay, the researchers treated hybrid tobacco cells with a type of salt, sodium-4-phenylbutyrate, known to help proteins fold properly. The treatment not only stopped the accumulation of protein aggregates, but also halted what had previously been the irreversible progression of cell death.

Going forward, the team plans to further investigate precisely how the accumulation of protein aggregates induces programmed cell death, specifically in relation to disease resistance and environmental stress in plants.

“We will also clarify the molecular mechanisms involved in the regulation of protein homeostasis,” Yamada said. “The ultimate goal is to establish a genetic improvement technique for developing crop varieties with better disease resistance and environmental stress tolerance by enhancing the function of maintaining protein homeostasis.”

The article can be found at: Ueno et al. (2019) Accumulation of Protein Aggregates Induces Autolytic Programmed Cell Death in Hybrid Tobacco Cells Expressing Hybrid Lethality.


Source: Tokyo University of Agriculture and Technology. Photo: Shutterstock.
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