Late maturity alpha-amylase (LMA) is a wheat genetic defect causing the synthesis of high isoelectric point (pI) alpha-amylase in the aleurone as a result of a temperature shock during mid-grain development or prolonged cold throughout grain development leading to an unacceptable low falling numbers (FN) at harvest or during storage. High pI alpha-amylase is normally not synthesized until after maturity in seeds when they may sprout in response to rain or germinate following sowing the next season crop. Whilst the physiology is well understood, the biochemical mechanisms involved in grain LMA response remain unclear. We have employed high-throughput proteomics to analyse thousands of wheat flours displaying a range of LMA values. We have applied an array of statistical analyses to select LMA-responsive biomarkers and we have mined them using a suite of tools applicable to wheat proteins. To our knowledge, this is not only the first proteomics study tackling the wheat LMA issue, but also the largest plant-based proteomics study published to date. Logistics, technicalities, requirements, and bottlenecks of such an ambitious large-scale high-throughput proteomics experiment along with the challenges associated with big data analyses are discussed. We observed that stored LMA-affected grains activated their primary metabolisms such as glycolysis and gluconeogenesis, TCA cycle, along with DNA- and RNA binding mechanisms, as well as protein translation. This logically transitioned to protein folding activities driven by chaperones and protein disulfide isomerase, as well as protein assembly via dimerisation and complexing. The secondary metabolism was also mobilised with the up-regulation of phytohormones, chemical and defense responses. LMA further invoked cellular structures among which ribosomes, microtubules, and chromatin. Finally, and unsurprisingly, LMA expression greatly impacted grain starch and other carbohydrates with the up-regulation of alpha-gliadins and starch metabolism, whereas LMW glutenin, stachyose, sucrose, UDP-galactose and UDP-glucose were down-regulated. This work demonstrates that proteomics deserves to be part of the wheat LMA molecular toolkit and should be adopted by LMA scientists and breeders in the future.

Background and Objectives: Gamma irradiation treatments are an effective option for sterilizing microbes and pests that damage wheat, however irradiation can alter the physical and nutritional properties of foods. In this study seven Australian wheat varieties were subjected to 0, 25, and 50 kGy treatments to examine the influence of high-dose irradiation on a range of wheat quality traits such as physical processing, protein composition and dough rheology. Findings:The traits most significantly affected by high doses of irradiation included flour color, unextractable polymeric protein (UPP), dough extensibility, dough resistance to extension, pasting viscosity, and starch damage.Rheological traits in the irradiated samples were adversely affected to such a high extent that they were not deemed suitable for end-product processing, including baking. Conclusions: High-dose irradiation, applied at 25 and 50 kGy, was shown to negatively impact most wheat quality traits tested. High-dose irradiation is not recommended for treating wheat if viscoelastic functionality is required for manufacturing of high-quality products.Significance and Novelty: Irradiation treatments significantly reduced the functionality of wheat quality traits tested. Irradiation significantly affected protein composition and structure, with a substantial reduction to the UPP fraction in wheat varieties tested. This change in protein functionality is likely linked to the decrease in dough viscoelastic properties.