Simple seed coating with peptides leads to big plant growth improvement

By Silvas Prince Kirubakaran, Ph.D., Postdoctoral Fellow and Wolf Scheible, Ph.D., Professor

Researchers at Noble are exploring the potential for native small peptides to be applied as seed coatings to enhance plant growth and return carbon back to the soil. By studying the effects of these peptides, they expect to expand knowledge that will lead to building better native grasses and legumes and to supporting grazing in marginal soils with reduced fertility and water.

Farmlands across the world are under a continuous threat due to erratic weather, climate variability, erosion and deteriorating soil health, resulting in soils with reduced carbon, nutrients and water storage capacity — which are vital for productive and sustainable agriculture.

To address these resource limitations, irrigation and synthetic fertilizers have been heavily used. However, this has led to the depletion of water reservoirs and environmental pollution with adverse effects on biodiversity, ecosystem functions and human health. To mitigate the effects of these unsustainable agricultural practices, it is important to improve plant resilience for better growth in lower-quality soils and in more extreme environments and to reverse the negative effects on soil health (the decrease of soil carbon content) and the atmosphere (increased carbon dioxide) by putting carbon back into the soil.

BUILDING BETTER NATIVE PLANTS

The Noble Research Institute Molecular Plant Nutrition Laboratory explores naturally occurring (i.e. genome-encoded) small plant peptides as a novel solution to alleviate various stresses in arable lands that limit crop and forage production.

Native small peptides applied as seed coatings now show promise to enhance aboveground plant growth and root growth in natural Oklahoma soil limited in fertility nutrients, such as nitrogen and phosphorus. Use of these small peptides can benefit farmers and ranchers by improving plant establishment and soil coverage, thus reducing soil erosion, and with reduced or without use of costly synthetic fertilizers. This can contribute to improvements in soil carbon content and eventually soil health. The bigger picture of this work is to build better native plants (grasses and legumes) to support grazing on marginal soils with reduced fertility and water.

IMPROVING GROWTH AND YIELD, AND RETURNING CARBON TO THE SOIL

Roles of small peptides in promotion of plant growth and development are known from laboratory studies with model plant species but still require translational research in crops. The Noble Research Institute Molecular Plant Nutrition Laboratory identified candidate small peptides in the model plant barrel clover (Medicago truncatula) and tested their effects on plant growth in vitro on agar plates in root rhizotrons and greenhouse experiments with artificial rooting media. Subsequently, the most interesting small peptides also were successfully tested with alfalfa, a close relative of Medicago truncatula. A peptide seed-coating strategy was developed and tested with alfalfa and winter wheat. Two different small peptides were found to strongly enhance root growth and development, as well as biomass yield under greenhouse (winter wheat and alfalfa), and close-to-natural growth conditions in native Oklahoma soil (alfalfa).

Under greenhouse conditions, one peptide increased winter wheat (NF101) biomass as much as 150% compared to plantlets that were not treated with the peptide. Experiments with alfalfa plantlets identified additional small peptides that enhanced biomass not only in laboratory and greenhouse environments but, importantly, also in natural, phosphorus-poor and growth-limiting Oklahoma soil. One peptide stimulated alfalfa growth as much as 77% compared to untreated control plants in the phosphorus-poor soil. A surprisingly large increase in root branching and biomass also was evident when this peptide was applied as a seed-coating agent.

Such results are highly encouraging, as they show that simple seed coating with specific small natural peptides result in big plant growth improvements without the need of genetic modifications. The results further suggest that peptides can be used to enhance plant resilience for better growth in poor soils and that peptides, through their effect on root growth, also are a tool to put photosynthetic carbon into the soil.

Future research aims at validating the effect of the small peptides in different forage crops and in different field sites with varying soil types. The ultimate goal is the introduction of small peptides as novel and affordable agrochemicals that increase producer profitability and benefit society through reduction of synthetic fertilizer use and its impacts on the environment and human health, while also helping to improve the quality of the soil.