In the never-ending war on diseases that pathogens bring upon crops, peptides are a vital ally in making gains for plant quality and yield output.

Peptides are short chains (between 2-50 links) of amino acids linked through peptide bonds. These short chains break down from larger protein chains or can be synthesized, which is what the scientists at Elemental Enzymes do. Michelle Leslie, R&D Director – Plant Directed BioControl for Elemental, explained that peptides play a number of critical roles in the development of plants and animals. The two main categories of peptide functions are 1) signaling and 2) direct action.

The peptide molecules can transmit information between cells or tissues within the same organism, or even between different ones — such as separate plants, or between a bacteria and plant. This is how Elemental’s proprietary peptide technology Vismax® works, as a signal alerting a plant’s immune system to boost itself against the threat of pathogens. Other types of peptides perform a non-signal function and can directly act on a pathogen, “punching” through its cellular membrane to result in its breakdown and death.

If you think of the direct-action peptides as soldiers fighting pathogens directly on the front line of attack, so to speak, you can think of the signaling peptides as advance scouts that observe and report — such as alerting a plant’s immune system to the initial damage caused by an insect feeding on one of its leaves.

Naturally occurring peptides in service to plants date back to the beginning of life, but they have been studied and synthesized for other research — including medical uses — only for a century or so. Some of the latest medical news in peptides is their potential for breaking up damaging plaques in the brains of Alzheimer’s patients, and in helping more precisely target certain vaccines for greater efficacy.

Peptides in agriculture

In 1921, scientists synthesized the first therapeutic peptide, insulin, to the benefit of hundreds of millions of diabetes patients. But though this preceded many life-changing developments in farming, Leslie noted that peptides didn’t really enter a period of research and investigation for ag purposes until about two decades ago. This was likely because the first plant genome was sequenced in 2000.

This stimulated a good deal of new biotechnological research on peptides and protein hydrolysates. These are essential plant biostimulants that can be broken down for their component peptides. The peptides can then be developed to beneficially target plant functions.

“I really think we’re just at the tip of the iceberg in understanding what all types of peptides, and their amino acids, can do for improving plant health,” Leslie said.

When Leslie joined Elemental in 2016, the Research and Development team was still broadly testing peptides relevant to drought stress. The research also included isolating applications for disease protection against conditions like Citrus Greening and Asian Soybean Rust (ASR). From this, the team discovered unexpectedly positive results from some peptides — one of which formed the basis for Vismax.

More uses with partner products

The technology behind Vismax complements and amplifies the benefits of disease-fighting inputs manufactured by Elemental’s industry partners. The Elemental team is investigating the possibilities in other peptides as well. There are up to 1,000 receptors on the surface of a plant connected to different tissues and tasks, which could be activated by certain peptides at times that most benefit the plant’s growth and immune support.

One avenue Leslie’s team is studying is working with the Vismax signal peptide to further amplify existing fungicide chemistry. Such fungicides are typically applied after a harmful fungus is visibly damaging the plant, but this would allow farmers to use a peptide-backed partner fungicide earlier in crop development. Elemental is finding effective results in trials on infections of wheat and barley in Australia and against soybean ASR in Brazil and Paraguay.

The Elemental team is driven to research agricultural problems that currently have limited solutions. To that end, another target Leslie named is Tar Spot on corn, a fungus that has caused severe yield loss in susceptible Midwestern hybrids since 2015. Her team has been conducting trials close to Elemental’s St. Louis headquarters over the past two years, gauging the effectiveness of signal peptides against Tar Spot.

“I am really proud about how robust our testing of everything is at Elemental, both in the lab and field, and focused on safety,” Leslie added. “Peptides are naturally occurring, and they’re going to degrade harmlessly into amino acids when their job in the plant is done. But while we expect them to be safe, we’re also proving it in our testing. You can always say, ‘Yes, our product is safe’ — but you definitely need to demonstrate it as well.”