Wheat (Triticum aestivum L.) grain proteome response to elevated [CO2] varies between genotypes

The impact of rising carbon dioxide concentration ([CO2]) in the atmosphere on wheat grain protein concentration and proteome was investigated in this study. Wheat genotypes (H45, SB003, SB062 and Yitpi) were grown in the Australian Grains Free-Air CO2 Enrichment (AGFACE) facility, Horsham, Victoria, Australia under ambient [CO2] (a[CO2], 391 μmol mol−1) and elevated [CO2] (e[CO2], 550 ± 20 μmol mol−1). Grain yield and grain protein concentration were measured. Global grain proteome comparison was carried out using stable isotope dimethyl labelling followed by liquid chromatography - mass spectrometry (LC-MS/MS). Grain yield was significantly increased at e[CO2], whereas protein concentration was significantly decreased and responses varied between genotypes. Proteome-wide analysis revealed that protein composition was also altered under e[CO2]. Grain protein concentration and composition of SB003 was very responsive to e[CO2]. Mainly storage proteins were decreased at e[CO2] and the responses varied between genotypes. These findings suggest that e[CO2] may have a major impact on grain protein quality and thus bread quality and human and animal nutrition. Further, these findings suggest that [CO2] insensitive cultivars can be identified for grain quality improvement under changing climate.