Dynamics of amino acid carbon and nitrogen and relationship with grain protein in wheat under elevated CO2 and soil warming

Abstract

The interactive effects of elevated atmospheric CO2 concentration ([CO2]) (700μmoll−1) and increased soil temperature (+2.4°C) on source-sink amino acid carbon (C) and nitrogen (N) dynamics and their relations to the concentration of grain protein components in winter wheat were investigated in greenhouse. Compared to the plants grown under ambient [CO2] (400μmoll−1) the contribution of N translocated after anthesis to the grain decreased, however, the total amount of N accumulated in the grain after anthesis increased in the plants grown under elevated [CO2]. Exposure of the plants to elevated [CO2] enhanced C allocation towards leaf at anthesis, but the allocation of leaf C and N as amino acid C and N was reduced by the combination of elevated [CO2] and soil warming. In addition, the amino acid C and N in the grain were also significantly decreased by the combined elevated [CO2] and soil warming treatment. The grain protein concentration correlated linearly with grain amino acid C but not with grain amino acid N. Collectively, the results indicated that modification of C and N metabolisms in the source and sink under future climate change scenarios may significantly decreased the protein concentration, and, thereby, the quality of wheat grain.