Effect of aluminum on the isozymes of the seedlings of two soybeans [Glycine max (L.) Merrill] varieties

Aluminum (Al) is not the necessary nutrient but the most abundant metal in the earth's crust. Isozymes of the seedlings of two soybean varieties (Zhechun No. 3 and Huachun No. 18) and their response to different Al treatments had been analyzed. The study showed that the responses to Al toxicity of different isozymes were quite different. Among these four isozymes, esterase (EST) isozyme was the least sensitive to Al toxicity. There was no distinct difference in the zymograms of EST under different Al treatments. Al toxicity enhanced to activity of peroxidase (POD) and induced some new bands to adapt it. Superoxide dismutase (SOD) was inhibited by Al toxicity and showed the descending of the activity and disappearing of some bands. The cytochrome-oxidase (COD) activity was also enhanced, but the enhancement of the activity of POD and COD occurred under the treatments of low Al Concentration. With the increasing of Al concentration, too much Al disturbed the expression of POD and COD isozymes, which showed that the activity of those isozymes descended. Furthermore, there was no consistence with the response to Al treatments among different bands of the same isozymes. Besides, there was some genotypic variation between two soybean varieties. The bands of these isozymes varies differently between two soybean varieties under the same Al treatments. Compared with huachun no. 18, Zhechun No. 3 had a stronger tolerance to Al stress relatively.