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Plants have a hormone that helps keep them hydrated

Researchers have identified a small hormone that helps plants retain water when they do not have access to it. The study has revealed that, when plants become dehydrated, the peptide CLE25 emerges and closes pores on the surface of the leaves to help prevent water loss.

Small chains of amino acids called peptide hormones are present in the blood of humans and animals that help keep our bodies in balance when the environment changes. Plants have hormones as well, which are called phytohormones, but little is known about their function.

Scientists at the RIKEN Center for Sustainable Resource Science (CSRS) in Japan set out to investigate if plant hormones respond to physical stress.

“Although we know that some peptide hormones in plants mediate cellular development, until now nobody had identified any that regulate responses to physical stresses such as dehydration,” said study first author Fuminori Takahashi.

The researchers examined CLE peptides that are synthesized in the roots. They also analyzed a hormone that is known to help close pores in response to drought stress known as ABA.

While applying CLE peptides to the roots of plants, the scientists discovered that only CLE25 boosted the accumulation of ABA in the leaves and led to pore closure. The experts found that the link between these two events was an increase in an enzyme that is needed to produce ABA.

Furthermore, CLE25 levels were found to increase in the roots of plants when water is scarce, leading to the same results. The experts set out to determine if CLE25 was mobile throughout a plant’s circulatory system.

“By using a high sensitive mass spectrometry system, and developing a screening system that can identify the mobile peptides moving from root to shoot,” explained Takahashi, the researchers were able to tag CLE25 molecules and observe their movement.

They found that CLE25 is, in fact, mobile. The team determined that this molecule likely interacts with others that are present in the leaves to trigger the production of ABA.

“Our research absolutely has applications in the real world and should contribute to the development of abiotic stress-resistant crops that take advantage of the mobile peptide system in plants,” said Takahashi.

The team is now actively working on such real-world applications.

“First, we are working on modified peptides that are more effective for stress resistance than the natural ones,” explained Takahashi. “Second, we are working on ways to mix functional peptides into fertilizer to enhance drought resistance of crops in the field.”

The study is published in the journal Nature.

By Chrissy Sexton, Staff Writer

Image Credit: RIKEN

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