Effect of NAA on the development, apoplastic peroxidase activities, and peroxidase isoenzymes in chicory root explants

NAA significantly modified the growth of chicory (Cichorium intybus L. cv. Bea) root explants cultured for 12d in either light or darkness. It also re duced the chlorophyll and the lignin content, peroxidase (EC 1.11.1.7) acti vities such as guaiacol peroxidase, auxin oxidase, and syringaldazine perox idase in light as well as in darkness. There was a positive relationship be tween specific syringaldazine peroxidase activity and the lignin content, a s well as between anionic peroxidases and lignification. Conversely, specif ic IAA oxidase activity and fresh weight were negatively correlated. NAA en hanced the expression of cationic peroxidase isoenzymes, particularly a per oxidase isoform pl 8.9 (Cicpx), in darkness and in light. This Cicpx was no t involved in the lignification process, NAA is suggested as exerting an in hibitory effect on the biosynthetic pathways of tetrapyrrole-containing com pounds.