Crop adaptation to air pollution ii. tolerance to so2 stress is regulated by oxidative and antioxidative characteristics and sulphur assimilation

Sulphur dioxide (SO2) and particulate matter (PM) are one of the major air pollutants emerging out of the industrial development and human activities. Plants exhibit differential sensitivity to SO2 pollution and its effects on plant growth can be both direct and/or indirect. We have earlier reported that a high SO2 stress contributes toward the S-nutrition of crops. The SO2 enriched environment significantly improved the activity of serine transacetylase (SAT) in all the experimental crops, however, the activity of O-acetylserine (thiol) lyase (OAS-TL) was enhanced chiefly in wheat but not in chickpea and barley. Further, the relative tolerance of crops to the particulate and gaseous pollutants was related to a lower level of superoxide and H2O2 radicals and lipid peroxidation and a higher level of antioxidants such as ascorbic acid and peroxidase activity. Relative tolerance of crops to the particulate and gaseous pollutants was related to a lower oxidative stress and a higher anti-oxidative defence that elevated SO2 contributes to S-nutrition of crops however, the threshold value of phyto-toxicity need to be determined across the crops.