Concentration changes of free amino acids in primary bean leaves after continuous and interrupted SO 2 fumigation and recovery

Abstract

It was found that in primary leaves of beans the concentration of free amino acids changes dramatically after fumigation with SO 2 at a concentration of 0·7 ± 0·1 ppm. In general, the SO 2 fumigation increases the total amount of free amino acids. Reduction of aspartic acid and glutamic acid and increase ammonium and some other amino acids seems to be the most characteristic feature of SO 2 fumigation. After 92 h recovery, a substantial decrease in the concentration of the total amino acids is observed, although it does not reach tontrol level. After shorter periods of treatment with SO 2 the recovery seems to the more complete. SO 2 reduces protein synthesis in fumigated plants in comparison with control plants. After recovery the protein content increases again to the control level in plants which have been treated up to 6 h/day. Longer fumigation periods always result in a decrease in the protein concentration. Some of the observed long duration phenomena can already be noted after only one hour's fumigation. Changes in the concentrations of the free amino acids were observed even when SO 2 fumigation had not yet produced any visible injury to the leaves. It seems possible to use changes in the amino acid concentrations for analyses of sublethal ‘hidden’ injuries caused by SO 2 fumigation.