Late Maturity Alpha-Amylase (LMA): Exploring the Underlying Mechanisms and End-Use Quality Effects in Wheat

Authors: Cannon, Ashley; MARSTON, ELLIOTT - Washington State University; KISZONAS, ALECIA - Washington State University; HAUVERMALE, AMBER - Washington State University; See, Deven

Submitted to: Planta
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/3/2021
Publication Date: 11/27/2021
Citation: Cannon, A., Marston, E.J., Kiszonas, A.M., Hauvermale, A.L., See, D.R. 2021. Late Maturity Alpha-Amylase (LMA): Exploring the Underlying Mechanisms and End-Use Quality Effects in Wheat. Planta. https://doi.org/10.1007/s00425-021-03749-3.
DOI: https://doi.org/10.1007/s00425-021-03749-3

Interpretive Summary: The Hagberg-Perten Falling Number (FN) test is the wheat industry’s standard method to gauge the predicted end-use quality of wheat flour. This test measures the structural integrity of starch in wheat grains by monitoring the gelling capacity of a slurry formed by mixing and heating a wheat flour/water mixture. When starch is degraded by hydrolytic enzymes, the gelling capacity of this mixture decreases, leading to a low FN and a decrease in end-use quality. One cause of low FN in wheat, late maturity alpha-amylase (LMA), leads to the production of high isoelectric point (high pI) alpha-amylases in the aleurone as a result of a temperature shock during mid-grain development or prolonged cold throughout grain development. During LMA, alpha-Amylase1 (alpha-Amy1) genes are expressed, resulting in the synthesis of enzymes that are retained in the grain until harvest and lead to huge economic losses for growers, millers, and bakers. This review describes the work being done to understand and eliminate LMA from wheat breeding programs and to determine if and how LMA-affected grain impacts end-use quality.

Technical Abstract: Late maturity alpha-amylase (LMA) leads to the expression and protein accumulation of high pI alpha-amylases during late grain development. This alpha-amylase is maintained through harvest and leads to an unacceptably low falling number (FN), the wheat industry’s standard measure for predicting end-use quality. Unfortunately, low FN leads to significant financial losses for growers. As a result, wheat researchers are working to understand and eliminate LMA from wheat breeding programs, with research aims that include unraveling the genetic, biochemical, and physiological mechanisms that lead to LMA expression. In addition, cereal chemists and quality scientists are working to determine if and how LMA-affected grain impacts end-use quality. This review is a comprehensive overview of studies focused on LMA and includes open questions and future directions.