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

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.