Elevated CO2 alleviates damage from Potato virus Y infection in tobacco plants

The assessment of plant resistance to viral infection under elevated carbon dioxide [ECO2] conditions is a key step in the development of plant–pathogen management. We quantified the aboveground biomass, foliar TNCs (total non-structural carbohydrates): Nitrogen ratio, and nicotine content of a tobacco cultivar (NC89) in two CO2 treatments after Potato virus YN (PVYN) infection. Foliar peroxidase (POD) activity, total amino acid content, soluble protein content, and chlorophyll content were also tested to explore the potential interaction of ECO2 and PVYN infection on tobacco secondary indices. ECO2 increased plant aboveground biomass, did not significantly influence TNCs or nitrogen content; while PVYN infection had adverse effects on biomass, markedly affected the later two indices; but no interactive effects between ECO2 and PVYN infection on these three indices were detected. As single factor, ECO2 or PVYN infection reduced chlorophyll content, while ECO2 increased the soluble protein content; interaction between two factors was observed on free amino acid and nicotine content. Variations in POD activity revealed that CO2 influenced infected plant primary production by reducing virus resistance cost. Results suggested that plants grown under ECO2 have alleviated damage of the virus infection or ECO2 delay the viral spread to some extent.