Improving alfalfa protein content and stability

Authors: Arther, Christina; Molodchenko, Andrew; Panke-Buisse, Kevin

Submitted to: North American Alfalfa Improvement Conference
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2024
Publication Date: 6/24/2024
Citation: Arther, C.M., Molodchenko, A.S., Panke-Buisse, K. 2024. Improving alfalfa protein content and stability. North American Alfalfa Improvement Conference. June 24-26, 2024.

Interpretive Summary: Alfalfa’s high protein content and role in sustainable agricultural production are driving interest in the use of alfalfa as a food for humans. One issue with using alfalfa in this way is the loss of protein that occurs after the leaves and stems are harvested. Whole proteins in plant tissues are degraded into smaller forms by the plant’s own enzymes after harvest. This represents a loss of nutrition and contributes to nitrogen emissions from farms, which affect both economic and environmental outcomes. In order to overcome this challenge, we have developed and optimized methods of measuring 1)plant enzyme activity that leads to protein loss and 2)the amount of whole protein within the plant tissue. Using these methods, we have shown that loss of whole protein occurs over time after harvest and that there is a sudden increase in plant enzyme activity six hours after harvest. This information coupled with ongoing experiments using these methods will help shed light on practices that may decrease the loss of protein in alfalfa and improve the utility of alfalfa as a food source for both dairy cows and humans.

Technical Abstract: Post-harvest degradation of alfalfa protein is a major obstacle to increasing alfalfa production for use in dairy and human food systems. We have developed a fluorescence intensity-based protease activity assay specifically for above ground plant tissue. We have also optimized a commercially available assay that measures the concentration of protein above 2.5 kilodaltons. We have used these two techniques to confirm that post-harvest protein degradation decreases the concentration of proteins larger than 2.5 kilodaltons within alfalfa leaves and stems. Unexpectedly, protease activity showed a sharp increase approximately six hours post-harvest. Understanding the plant mechanisms underpinning post-harvest control of protease activity may lead to new strategies for enhanced conservation of forage protein. Ongoing experiments will focus on screening alfalfa varieties for decreased protease activity and increased intact protein. Identifying these varieties could help with future breeding efforts or inform variety selection to increase alfalfa performance both as a dairy forage and potential as a human food source.