Barley yellow dwarf virus infection and elevated CO₂ alter the antioxidants ascorbate and glutathione in wheat

Plant antioxidants ascorbate and glutathione play an important role in regulating potentially harmful reactive oxygen species produced in response to virus infection. Barley yellow dwarf virus is a widespread viral pathogen that systemically infects cereal crops including wheat, barley and oats. In addition, rising atmospheric CO₂ will alter plant growth and metabolism, including many potential but not well understood effects on plant-virus interactions. In order to better understand the wheat-BYDV interaction and any potential changes under elevated CO₂, the total concentration and oxidised fraction of ascorbate and glutathione was measured in leaves of a susceptible wheat cultivar (Triticum aestivum L. 'Yitpi') infected with Barley yellow dwarf virus-PAV (Padi Avenae virus) and grown under elevated CO₂ in controlled environment chambers. Virus infection decreased total leaf ascorbate and glutathione concentrations and increased the fraction of oxidised ascorbate (dehydroascorbate). Elevated CO₂ decreased the fraction of oxidised ascorbate. In this work, we demonstrate that systemic infection by a phloem-restricted virus weakens the antioxidant pools of ascorbate and glutathione. In addition, elevated CO₂ may decrease oxidative stress, for example, from virus infection, but there was no direct evidence for an interactive effect between treatments.