Scientists find protein that makes plants more drought-resistant

An international team of researchers has narrowed in on a protein that seems to enhance plants’ drought tolerance.

The research, published in New Phytologist, could help to make crops more resistant to increasingly severe droughts.

The protein, called AtMC3, is found within a plant’s phloem: tissues that transfer sugars and other materials from leaves to the rest of the plant.

AtMC3 is found within specific cells of the phloem, called companion cells. It’s in a class of proteins called metacaspases, which have previously been linked to plant other plant stress responses like pathogens and wounds.

Lines of thale cress plants
Arabidopsis thaliana, or thale cress: the plant used in the study. Credit: CRAG

The researchers used thale cress (Arabidopsis thaliana), a small plant commonly used as a model organism in labs, to study the effect of the protein.

They genetically modified thale cress to have different  AtMC3 levels, as well as making the protein glow with a fluorescent tag so that they could see where in the plants it was appearing.

Fluorescence photo of plant stem
Fluorescence microscopy image of the tip of the root of Arabidopsis thaliana showing specific expression of the protein AtMC3 (green) in the companion cells of the phloem vascular tissue. Credit: CRAG

They then grew the plants for several weeks, testing them for various stressors and chemical expressions, including water-scarce conditions.

The researchers found that plants with less AtMC3 were less sensitive to a hormone in the plant called abscisic acid (ABA). ABA is a stress hormone that triggers protections in a plant when there’s less water around.

They also found that increasing the levels of AtMC3 increased plants’ survival rates and their ability to photosynthesis when water was scarce.

Diagram pointing to phloem of plant and plant cells with drought-resistant protein
Vascular plant tissue include xylem, which transports water and nutrients from the roots of a plant to the leaves, while phloem transports sugars and other material from the leaves back down to the roots. AtMC3 was found only in the phloem. Credit: CRAG

Increased AtMC3 levels didn’t cause any other damage to the plant.

Dr Eugenia Pitsili, who did the research at the Centre for Research in Agricultural Genomics in Spain, says that this “is a key finding to be able to fine-tune early drought responses at the whole plant level without affecting growth or yield in crops”.

The researchers are now interested in finding the mechanism behind AtMC3’s helpfulness, which could eventually help to breed more drought-tolerant food.

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