PEROXIDASE-ACTIVITIES IN THE FLORAL TISSUES OF TRADESCANTIA CLONE BNL-4430 TREATED WITH MALEIC HYDRAZIDE ALONE, X-RAYS ALONE, OR IN COMBINATIONS

Changes in peroxidase activity in young inflorescences of Tradescantia clone BNL 4430 were investigated after treating with maleic hydrazide (MH) alone, X rays alone, or MH and X rays in combinations. MH is a p romutagen known to be activated into a mutagen in plant cells. The tre atments with MH were conducted for 4 h at a fixed concentration of 1 m RI, and the X-ray doses applied were 768 to 882 mGy. For the combined treatments, X rays were delivered either 20 h before starting, or 2 or 20 h after completing the 4-h MH treatments. The treatments with MH a lone and X rays alone both increased peroxidase activity, as compared with the controls. The combined treatments of delivering X rays 20 h b efore starting the MH treatments resulted in marked increases 11 the a ctivity of this enzyme. However, the increases in peroxidase activity after the combined treatments of X-raying 2 h after completing the MH treatments were small, and the activity rather decreased by X-raying 2 0 h after completing the MH treatments. These results are consistent w ith our earlier findings that clear syneristic effects of MH and X ray s in inducing somatic pink mutations in the stamen hairs of clone BNL 4430 were detected by treating with X rays before MH treatments, where as antagonistic effects of MH and X rays were often observed by delive ring X rays during or after MH treatments (Xiao and Ichikawa, 1995). I t is therefore highly likely that peroxidase is certainly involved in the activation of MH into a mutagen, and that the increases and decrea ses in peroxidase activity after different combined treatments are rel ated to the occurrences of synergism and antagonism, respectively, bet ween MH and X rays.