The influence of an air pollutant, peroxyacetyl nitrate (PAN), on 3-indoleacetic acid (IAA) and its metabolites in tobacco plants was studied. Plants were administered IAA-2-14C immediately before or after gassing with PAN. After 8 hr metabolism in the dark or in the light the plants were separated into shoot tip and damaged and undamaged leaf areas prior to analysis. PAN-treated plants which metabolized in the light and produced partially damaged leaves showed a relative increase in unmetabolized IAA in the leaves compared to control treatments. Several suspected indole conjugates from leaves of PAN-treated plants contained relatively less label than controls. Plants which metabolized in the dark and showed no visible external damage also demonstrated changes in indoleacetic acid metabolism. The changes were qualitatively different however from those observed in damaged tissue. Undamaged PAN-treated tissue consistently had less of certain unidentified compounds. It was concluded that PAN is capable of causing biochemical lesions in indole metabolism prior to the expression of visible damage.
展开▼
