Addressing global wheat issues one-grain-at-a-time, based on gliadin alleles

For decades, electrophoretic analysis of wheat‐gliadin composition has been a valuable approach to elucidating the genetic constitution of a grain sample, providing this information even at the single‐grain level. An early example was the characterisation of the mix of wheat varieties in a truckload of wheat suspected of being stolen from a country wheat silo in north‐western NSW. Much wider uses of gliadin composition have included tests of genetic non‐uniformity (the presence of biotypes) to study the reasons for variations in grain quality for specific varieties.In the global picture, Australian varieties were found to have considerable non‐homogeneity, but not so great as for some countries. However, it can be argued that a degree of genetic non‐homogeneity can offer some advantages. In parallel with these studies, we examined the global range of cultivars for possible genetic erosion during the twentieth century; no general narrowing of genetic polymorphism was found throughout this period. The analysis of gliadin alleles for many wheat cultivars revealed important relationships at country and regional levels. For example, the cultivars of certain Australian states showed closer relatedness than for other combinations of states. Internationally, Australian wheats were more closely related to varieties from Mexico than to cultivars of many other countries, based on a global set of 290 cultivars bred throughout the twentieth century.