The influence of elevated CO2 on the activities of antioxidative enzymes in two soybean genotypes

Abstract

The effects of ele vated compared to current atmospheric CO2 concentration (720 and 365 µL L -1 , respec­ tively) on antioxidative enzymatic activities of two soybean (Glycine max (L.) Merr.) genotypes (R and S) grown in open-top field chambers were investigated. Enzymatic activities of leaves collected 40, 47, 54 and 61 d after plant­ ing were measured. Elevated CO2 significantly decreased activities of superoxide dismutase (SOD, EC 1.15.1.1), peroxidase (POD, EC 1.11.1.7), catalase (CAT, EC 1.11.1.6), ascorbate peroxidase (APOD, EC 1.11.1.7), gluta­ thione peroxidase (GPOD, EC 1.11.1.9) and glutathione reductase (GR, EC 1.6.4.2) in both genotypes. The activi­ ties of dehydroascorbate reductase (DAR, EC 1.8.5.1) and monodehydroascorbate reductase (MDAR, EC 1.1.5.4.) increased in genotype S, but decreased in genotype R under elevated CO2. Elevated CO2 decreased rubisco activity and rubisco, chlorophyll, carotenoids and total soluble protein contents in both genotypes. Results indicate that con­ stitutive antioxidative enzymatic activities may decrease in a high-CO2 world. Significant CO2 × genotype interac­ tions, however, suggest that there may be key genotypic differences in response patterns, potentially conferring differential resistance to biotic and abiotic stress.