Newly Discovered Hormone Helps Keep Plants from Dehydration

Researchers at the RIKEN Center for Sustainable Resource Science (CSRS) in Japan have discovered a small hormone that helps plants retain water even when none is available in the soil. The study, published in Nature, shows how the peptide CLE25 moves from the roots to the leaves when water is scarce and helps prevent water loss by closing pores in the leaf surface.

The team at RIKEN CSRS wanted to find out if plant hormones respond to abiotic stress. They looked at CLE peptides that are synthesized in the roots, and at abscisic acid (ABA), a hormone that accumulates in the leaves and help close pores in response to drought. Applying many CLE peptides to plant roots showed that only CLE25 led to increased ABA in the leaves and pore closure. The team concluded that the link between these two events was the increase in an enzyme necessary for making ABA. They also observed that CLE25 levels increased in the roots of plants subjected to dehydration stress, leading to the same results.

To determine if CLE25 moves through the plant circulatory system, the team used high sensitive mass spectrometry system, and developed a screening system that can identify movement of the mobile peptides from root to shoot. The researchers were able to tag CLE25 molecules and observed their movement from the roots to the leaves, indicating that it was indeed a mobile hormone and that it likely interacted with other molecules in leaf to produce ABA.

Before investigating how CLE25 induces ABA synthesis once it arrives at the leaf, the team created mutant plants that lacked CLE25 or ABA and performed several control experiments that confirmed their findings. After only three hours of dehydration, plants without CLE25 already showed 7 times less leaf ABA and had lost more water than control plants. Finally, the team examined several mutants and discovered that BAM1/BAM3 receptors in leaf were the link between CLE25 and ABA production.

For more, read the press release at the RIKEN CSRS website.


 

This article is part of the Crop Biotech Update, a weekly summary of world developments in agri-biotech for developing countries, produced by the Global Knowledge Center on Crop Biotechnology, International Service for the Aquisition of Agri-Biotech Applications SEAsiaCenter (ISAAA)

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