Effects of the herbicide paraquat on growth and superoxide dismutase levels in four species of southern pine callus

Crude extracts of the pine callus were prepared and subjected to electrophoresis and enzyme assays. Multiple bands of Cu-Zn SOD were found in all the lines tested and 1 band of Mn SOD activity was also present in all four species. Banding patterns varied from species to species, but band number was not affected by paraquat treatment.

Quantitation of SOD levels through densitometer scan analysis of polyacrylamide gels as well as enzyme assays indicated a significant increase in short leaf SOD content over that of the controls when grown on 10 ^-8M and 10^-6M paraquat. SOD levels in loblolly, Virginia and white pine callus neither increased nor decreased significantly in response to paraquat treatment.

These results may indicate that the increased levels of SOD in short leaf calli may be providing protection against the paraquat toxicity and thus allowing growth to continue as normal.