Elevated CO₂ and Nitrogen dose affect grain ionome, grain morphology and associated gene expression in wheat (Triticum aestivum L.)

The rise in atmospheric CO₂ levels impacts humankind by threatening food and nutritional security. The strong correlation between crop yield and grain weight in cereals is an essential component of yield stability. Further, improving grain protein and mineral nutrient content is a crucial breeding target for cereal crops. The study was performed to understand the interactive effects of elevated CO₂ (EC) and nitrogen (N) fertilization on grain ionome, grain yield parameters, grain morphology, and the expression of genes related to grain morphology. The changes in ionome and grain parameters were examined in response to two N levels optimal N (ON: 500 mg/pot) and high N (HN: 625 mg/pot) along with atmospheric CO₂ enrichment [ambient (CO₂) of 400 ±10 ppm and elevated (CO₂) of 700 ±10 ppm]. Grain ionome (N, K, Ca and Fe) showed a general decrease in EC-grown wheat plants. The expression of genes related to grain length (TaGL3 and TaGL7) were upregulated, and those genes related to grain width (TaGW2 and TaGW6) were downregulated under EC in maturing spikelet of wheat. In the case of TaSnRK2, the expression was promoted by EC in HN treatment. The complex regulation of source and sink-associated gene transcript abundance indicates an EC mediated alteration in N and sugar signalling in wheat.