Exploring preharvest sprouting (PHS) and late-maturity alpha-amylase (LMA) in wheat through proteomics: A review

Abstract

Climate fluctuations have made it increasingly difficult for growers to maintain the quality and quantity of their grain to a degree that is satisfactory to buyers. Challenges for growers are preharvest sprouting (PHS) and late-maturity alpha-amylase (LMA), which are influenced by weather and genetic differences between varieties. Both lead to the expression of alpha-amylase enzymes in wheat (Triticum aestivum L.) grain, which degrade starches in the endosperm. Starch degradation drastically reduces the quality of food products that can be made from the affected wheat, leading to substantial financial losses for the grain industry. Identifying PHS and LMA depends on the Hagberg–Perten falling number (FN) test. While the industry standard, the FN test is not easily deployable at farms or elevators due to capital equipment costs and low test throughput. As a result, there is an increased risk of inadvertent mixing of affected grain with unaffected grain. Emerging literature suggests that LMA impacts end-use quality differently than PHS. However, the FN test is unable to differentiate between PHS and LMA, which limits grain management strategies. Cost-effective tests that can rapidly detect and differentiate between PHS and LMA may help to prevent inadvertent mixing and enhance breeding for tolerant varieties. A deeper understanding of changes in protein expression during PHS and LMA is needed for improving test development and targeted breeding. This review seeks to define the current understanding of changes in the wheat grain proteome during PHS and LMA, and the impact on end-use quality of wheat.