Novel genetic control of alpha-amylase activity during pre-harvest sprouting indicated by RNA sequencing of soft winter wheat varieties Cardinal and Logan

Authors: Penning, Bryan

Submitted to: Plant Gene
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/24/2025
Publication Date: 2/28/2025
Citation: Penning, B. 2025. Novel genetic control of alpha-amylase activity during pre-harvest sprouting indicated by RNA sequencing of soft winter wheat varieties Cardinal and Logan. Plant Gene. 42. Article 100495. https://doi.org/10.1016/j.plgene.2025.100495.
DOI: https://doi.org/10.1016/j.plgene.2025.100495

Interpretive Summary: Pre-harvest sprouting can cause up to 50% crop yield loss or 30% loss in crop value. It is an issue in wheat in the U.S. and world-wide. A major part of soft winter wheat value loss comes from reduction in Falling Number, the industry standard measure of pre-harvest sprouting damage. Falling Number below 300 results in a price reduction while Falling Number below 250 negatively influences grain quality and can lead to crop rejection at the grain elevator or mill. Current pre-harvest sprouting resistance genes rely on changes to seed dormancy that could impact agronomic practices such as double cropping wheat with soybean or establishment of winter wheat root systems after planting. During pre-harvest sprouting, alpha-amylase activity increases, resulting in increased cleavage of starch molecules and reduced Falling Number. This research found a gene expressed in the wheat variety Logan that may phosphorylate starch and make it resistant to alpha amylase cleavage. Falling Number was 33% higher in Logan under severe artificially irrigated pre-harvest sprouting and 66% higher under natural pre-harvest sprouting events. By introduction of this gene, wheat breeding programs will be able to develop soft winter wheat varieties less affected by pre-harvest sprouting, allowing agronomic practices dependent on low dormancy to be less impacted. This would benefit growers, flour millers and bakers, our key stakeholders. Other genes related to seed dormancy that could impact pre-harvest sprouting were also discovered. These genes will be of interest to wheat breeders for overall improvement of pre-harvest sprouting resistance which ultimately benefits farmers, millers, and bakers through improved wheat quality.

Technical Abstract: Pre-harvest sprouting, the germination of wheat seeds still in the field, leads to decreased crop value and increased crop losses around the world. Pre-harvest sprouting causes low Falling Number that results in price reductions or rejection of soft winter wheat grain at the flour mill or grain elevator. Several pre-harvest sprouting resistance genes have been found. However, they act through seed dormancy-related signaling pathways which can affect winter wheat root establishment for overwintering and double-cropping wheat with soybean. Here, RNA sequencing has been performed on soft red winter wheat varieties Cardinal and Logan with 91% of 1978 markers common between them but differing in pre-harvest sprouting resistance. Between 64 and 660 genes were differentially expressed in comparisons between Cardinal and Logan at different time points of seed development. A glucan water diskinase was a top five differentially expressed gene located near a recently reported quantitative trait locus for pre-harvest sprouting. It has potential to reduce alpha amylase activity and starch degradation during pre-harvest sprouting. Slowing starch degradation reduces starch damage, keeping flour pasting viscosity and Falling Number higher under pre-harvest sprouting conditions. Slowing starch damage rather than altering seed dormancy would reduce impact on some agronomic traits.