Chamber and Field Studies demonstrate Differential Amb a 1 Contents in Common Ragweed Depending on CO₂ Levels

Abstract

Although atmospheric carbon dioxide (CO2) has no apparent direct effect on human health, it does have direct effects on plants. The present study evaluated the influence of increased CO2 levels on the concentration of allergens from common ragweed pollen by setting up a chamber study to model future air conditions and a field study to evaluate current air conditions. For the chamber study, we established 20 ragweed plants in an open top chamber under different CO2 levels (380-400, 500-520, 600-820, and 1,000-1,100 parts per million [ppm]). For the field study, we established ragweed plants in rural (Pocheon, Gyeonggi-do; mean CO2 320 +/- 54.8 ppm) and urban (Gangnam, Seoul; mean CO2 440 +/- 78.5 ppm) locations. Seeds of the common ragweed (Ambrosia artemisiifolia) were obtained from Daejin University. The Amb a 1 protein content of pollen extracts was quantified using a double sandwich enzyme-linked immunosorbent assay. In our chamber study, the median concentration of Amb a 1 in pollen increased with increasing in CO2 concentration (1.88 ng/mu g in 380-400 ppm CO2; 3.14 ng/mu g in 500-520 ppm CO2; 4.44 ng/mu g in 600-620 ppm CO2; and 5.36 ng/mu g in 1,000-1,100 ppm CO2). In our field study, we found no significantly different concentration of Amb a 1 between the pollen extracts at the Pocheon (mean standard deviation, 1.63 +/- 0.3 ng/mu g pollen in 320 +/- 54.8 ppm CO2) and the Gangnam (2.04 +/- 0.7 ng/mu g pollen in CO2 in 440 78.5 ppm CO2) locations, although the concentration of Amb a 1 was increased in the Gangnam than in the Pocheon locations. Our results suggest that future increases in CO2 levels to more than 600 ppm will significantly elevate the Amb a 1 content in common ragweeds, although the current different CO2 levels do not cause differences in the Arnb a 1 content of ragweed pollen.