Shotgun proteomics of the barley seed proteome

Ramamurthy Mahalingam

Barley seed proteins are of prime importance to the brewing industry, human and animal nutrition and in plant breeding for cultivar identification. To obtain comprehensive proteomic data from seeds, total protein from a two-rowed (Conrad) and a six-rowed (Lacey) barley cultivar were precipitated in acetone, digested in-solution, and the resulting peptides were analyzed by nano-liquid chromatography coupled with tandem mass spectrometry. The raw mass spectra data searched against Uniprot's Barley database using in-house Mascot search engine identified 1168 unique proteins. Gene Ontology (GO) analysis indicated that the majority of the seed proteins were cytosolic, with catalytic activity and associated with carbohydrate metabolism. Spectral counting analysis showed that there are 20 differentially abundant seed proteins between the two-rowed Conrad and six-rowed Lacey cultivars. This study paves the way for the use of a top-down gel-free proteomics strategy in barley for investigating more complex traits such as malting quality. Differential abundance of hordoindoline proteins impact the seed hardness trait of barley cultivars.