Graduate Student Auburn University Auburn, Alabama
Body of Abstract: Tropospheric ozone [O3] is a secondary pollutant formed from the photochemical oxidation of volatile organic compounds in the presence of nitrogen oxides and is one of the most damaging air pollutants to crops. O3 impacts plants at the whole plant, leaf and cellular level and can lead to decreases in crop yield and overall biomass accumulation. Increased O3 exposure has also been shown to have secondary impacts on plants by altering the incidence of pests or pathogens, or by mediating the ability of a plant to respond to these pressures. O3 initially enters through the stomata, and reacts quickly upon entry inside the plant, by decomposing into reactive oxygen species (ROS) such as hydrogen peroxide, singlet oxygen and hydroxyl radicals. Both O3 and pathogen presence trigger ROS signaling, which can be linked to the hypersensitive response plants sometimes exhibit in response to pathogen pressure. Due to the often synergistic outcomes of plant responses to biotic and abiotic stress, we used the model pathosystem Capsicum annum-Xanthomonas perforans to investigate potential crosstalk and tradeoffs of this interaction. We evaluated the impact of elevated O3, individually and in combination with X.perforans infection, under open-top chamber field conditions. We included both a susceptible and resistant variety of C. annuum to X. perforans. Our findings demonstrate that an increase in tropospheric O3 will limit rates of photosynthesis and stomatal conductance, and lower overall weights of aboveground biomass. Maximum rates of biochemical mechanisms such as carboxylation and electron transport were also both also impacted by elevated O3. By investigating the physiological response, host plant transcriptomes, and susceptibility of C. annuum to relevant pathogens, we may begin to understand the complex interaction between abiotic and biotic stresses that may be imposed given future climate change predictions.