Effect of auxin type on the total phenols synthesis and some enzymatic proteins activity in maize callus from seeds irradiated to gamma radiation

Secondary metabolites of plants widely used in the medicinal and cosmetic industries, can be produced by tissue culture. In vitro production of these secondary metabolites is affected by various factors such as the type and concentration of phyto regulators. In this study, 2,4-dichlorophenoxyacetic acid (2,4-D) and 2-methoxy-3,6-dichlorobenzoic acid (Dicamba) effect on phenolic compounds synthesis as well as Phenylalanine ammonia lyase (PAL), tyrosine ammonia lyase (TAL), Polyphenoloxidase (PPO), peroxidase (POD), Catalase (CAT) and Ascorbate Peroxidase (APX) activities from root explants have been studied. The root explants come from the seeds in vitro germination of maize irradiated (200 and 300 grays) or not irradiated (control) with gamma radiation. The results obtained showed that the auxin type had a very highly significant effect (p <0.001) on all parameters studied. Callus induced on medium containing 2,4-D gave a higher content of phenolic compounds, PAL, TAL, PPO, POD, CAT and APX than callus induced on medium containing dicamba. The highest content of total phenols (76.971 µmol/g fresh callus) was obtained in callus from 300 grays. By cons, the contents of POD, PAL, TAL, CAT and APX (4.034; 0.031; 0.145; 1315.596 and 2461.714 mmol/min/g fresh callus) were obtained in callus from 200 grays.