Proteomic profiling of wheat and barley grain for cultivar and provenance identification

The proteomes of wheat and barley grain cultivars have evolved through genetic variability and environmental factors. The ability to identify different cultivars, farm origin, and quality of wheat and barley grain are becoming increasingly important to farmers, processors, and food manufacturers. This will help them to diversify into higher value boutique products, or just to add value through security and traceability to bulk grain or flour exports. This project aims to use modern proteomic techniques and transcriptomics to discover proteins that can be used as biomarkers in wheat and barley grain to identify crop cultivars, grain provenance (farm origin) and possibly grain quality. Firstly, several protein extraction methods were assessed for optimal protein yield and diversity. This was important for maximising the discovery of potential protein biomarkers through proteomic analysis. By applying Tandem Mass Tags (TMTs) labelled shotgun proteomics, a subset of grain proteins was detected from wheat and barley that show statistically significant differential expression between different cultivars and different farm locations. Indeed, serpin and chitinase proteins (observed to be involved in stress response) were found to be differentially expressed in the wheat and barley sample proteomes. The results also indicated that the differentially expressed proteins from wheat and barley grain have the potential to be used as biomarkers for probable quality traits. The assigned protein biomarkers between cultivars or a particular cultivar from a different environment (farm location) have almost identical functional summaries (gene ontology [GO] Slims). Investigations into wheat mRNA expression between cultivars showed GO Slims that were analogous to the proteomic results. Further experiments involving proteomics and common traditional quality testing such as, 1000-kernel weight, farinograph, extensograph, baking tests and falling number, are needed to answer this question, and is beyond the scope of this project. Protein-based tests to identify cultivar, farm origin, and grain quality have the potential to address these needs in a manner that would be faster relative to existing quality controls.