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Globulin Expression in Grain of Australian Hard Wheat Cultivars Is Affected by Growth Environment

¹Faculty of Agriculture and Environment, University of Sydney, NSW 2006, Australia. ²Kulliyyah of Science, International Islamic University of Malaysia, Kuantan, Pahang, Malaysia. ³Corresponding author. Phone: +61 2 8627 1017. Fax: +61 2 8627 1099. E-mail: les.copeland@sydney.edu.au

Our aim was to study changes in wheat proteomes across different growth locations as the first step in linking protein composition with functional changes in grains produced with commercial production systems. Soluble and insoluble proteins were extracted sequentially from grain of three commercial wheat cultivars grown at four locations in New South Wales, Australia, during a single season. Bands were separated with SDS-PAGE and identified by peptide mass fingerprinting. Quantitative changes in the electrophoretic patterns were observed mainly in the insoluble polypeptides of molecular mass 40,000–70,000 for all three cultivars grown at two of the four locations. These proteins were identified as mainly globulin and serpin isoforms, as well as triticin. Other proteins with changed expression included disease-resistance proteins, class III peroxidase, starch branching enzyme I, β-amylase, and storage proteins. Two-dimensional electrophoretic analysis was performed on two of the same wheat cultivars grown at one of the locations during two consecutive seasons. Protein spots that varied between seasons consisted of globulin and serpin isoforms, triticin, HMW glutenin, γ-gliadin, starch branching enzyme IIb, and α-amylase. The implications of the upregulation of globulin and triticin on whole meal flour quality, through their participation in polymerization of the gluten network, are considered.