A Peptide That Helps Plants Deal With Salt Stress

A research group in Japan has discovered a peptide that helps increase salt tolerance in plants.

AsianScientist (Jun. 1, 2018) – Researchers at the RIKEN Center for Sustainable Resource Science (CSRS) in Japan have discovered a hormone-like peptide in plants that helps increase their tolerance to excessive salt. Their findings are published in the Proceedings of the National Academy of Sciences.

Just like animals, plants are affected by physical stress that can stunt growth and affect survival. For example, when the soil is too salty, it draws water out from the plants. Excessive amounts of sodium are also absorbed by the plants, which can have toxic effects. This may impact the yields of important crops.

Plants have automatic defenses against physical stress that involve peptide hormones, although the precise roles of these peptide hormones remain poorly characterized. Because peptides are basically very small proteins, the team at RIKEN CSRS began looking for peptide hormones related to salinity tolerance by using a microarray analysis to find small coding genes that were expressed at high levels in plants experiencing high salinity conditions.

The researchers then created transgenic plant lines that each overexpressed one of the candidate genes identified by the microarray analysis. They measured how well these transgenic plants fared in a salinity stress test and found that four of these plants showed better tolerance than control plants. Subsequently, the researchers investigated the gene that induced the greatest tolerance, AT13.

Experiments confirmed that levels of the AT13 peptide naturally increased when plants were subjected to salt stress. The team went further and determined the exact portion of the peptide that was important for high salt tolerance. To do so, they synthesized pieces of the AT13 peptide and treated plants with the synthetic peptide fragments. They observed that plants receiving one section of the peptide, which they called AT13-5, could tolerate salt stress just as well as plants overexpressing the AT13 gene.

“Peptides are natural compounds that are safer than genetically modified plants,” said Dr. Kentaro Nakaminami of RIKEN, who is a co-author of the study. “Additionally, potential supplements made from synthetic peptide fragments will be easy to apply to different species of plants.”

Understanding exactly what the AT13-5 peptide fragment does to increase salinity tolerance was the next step. The researchers demonstrated that the peptide did not affect how much water the plants lost. This meant that it likely helps plants combat the excess sodium that accumulates inside the plants.

“We found the first functional evidence for improved salinity stress tolerance in plants in response to treatment with a small peptide. This is a first step towards the production of new agricultural supplements for plants growing in high salinity conditions,” said Nakaminami.

The article can be found at: Nakaminami et al. (2018) AtPep3 is a Hormone-like Peptide That Plays a Role in the Salinity Stress Tolerance of Plants.


Source: RIKEN; Photo: Shutterstock.
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