Genetic susceptibility to late maturity alpha-amylase (LMA) in wheat (Triticum aestivum L.) results in increased alpha-amylase activity in mature grain when cool conditions occur during late grain maturation. Farmers are forced to sell wheat grain with elevated alpha-amylase at a discount because it has an increased risk of poor end-product quality. This problem can result from either LMA or preharvest sprouting, grain germination on the mother plant when rain occurs before harvest. Whereas preharvest sprouting is a well-understood problem, little is known about the risk LMA poses to North American wheat crops. To examine this, LMA susceptibility was characterized in a panel of 251 North American hard spring wheat lines, representing ten geographical areas. It appears that there is substantial LMA susceptibility in North American wheat since only 27% of the lines showed reproducible LMA resistance following cold-induction experiments. A preliminary genome-wide association study detected six significant marker-trait associations. LMA in North American wheat may result from genetic mechanisms similar to those previously observed in Australian and International Maize and Wheat Improvement Center (CIMMYT) germplasm since two of the detected QTLs, QLMA.wsu.7B and QLMA.wsu.6B, co-localized with previously reported loci. The Reduced height (Rht) loci also influenced LMA. Elevated alpha-amylase levels were significantly associated with the presence of both wild-type and tall height, rht-B1a and rht-D1a, loci in both cold-treated and untreated samples.

A developmentally regulated, novel β-amylase gene (ESDbamy) from Hordeum vulgare L. has 76% amino acid similarity with a previously described barley β-amylase. However, the 3' -end sequences of these β-amylases were different. The glycine-rich repeats, which are signature sequences of endosperm-type β-amylases, are absent in this novel ESDbamy gene. ESDbamy is highly expressed in the caryopsis during early development; however, it is not expressed in other tissues. Early seed development-specific (ESD) β-amylase mRNA levels and enzyme activities were higher in a shrunken endosperm mutant, seg8, than in the wild type. Seg8 has defective endosperm development, reduced starch synthesis and elevated monosaccharide concentrations