EFFECTS OF X IRRADIATION AND INDOLEACETIC ACID ON SPECIFIC PEROXIDASE ISOZYMES IN PITH TISSUE OF A NICOTIANA AMPHIPLOID

Two electrophoretically anodal peroxidase bands, designated A3 and A4, which normally develop in zymograms of incubated pith tissue of a Nicotiana amphiploid, were inhibited by the inclusion of 0.10 mg indoleacetic acid (IAA) in a liter of culture medium. The visibility of the bands was not inhibited, however, if the pith was irradiated or if unirradiated pith blocks were incubated in either irradiated IAA-containing media or in media supplemented with irradiated IAA. Irradiation inactivates IAA in media, and according to this isozyme test, damages the capability in irradiated tissue of using exogenously supplied IAA. Radiationinduced damage to IAA metabolism caused radiation-induced peroxidase stimulation, shown in the more rapid appearance of isozyme bands A3 and A4.