CHANGES IN SOLUBLE AND CELL WALL-BOUND PEROXIDASE-ACTIVITIES WITH GROWTH IN ANOXIA-TREATED RICE (ORYZA-SATIVA L) COLEOPTILES AND ROOTS

The activity of soluble and cell wall-bound (1.0 M NaCl extractable) peroxidase in relation to growth of anoxia-grown Indica rice seedlings (Oryza sativa L. cv. Taichung Native 1) was examined. Guaiacol and syringaldazine were used to assay for peroxidase activity. In air-grown coleoptiles, guaiacol or syringaldazine peroxidase activity initially decreased or remained constant, respectively, in the early period but then both increased as coleoptile elongation ceased. In air-grown roots, both guaiacol and syringaldazine peroxidase activities decreased slightly during the growth period. In response to anoxia, coleoptile elongation was stimulated but root growth was seriously inhibited. Anoxia induced a significant decrease in activity of cell wall-bound guaiacol and syringaldazine peroxidase while soluble peroxidase activity was not affected in coleoptiles. In contrast to coleoptiles, anoxia-grown roots showed an increase in cell mall-bound guaiacol and syringaldazine peroxidase activities. When transferred to aerobic conditions, cell wall-bound guaiacol and syringaldazine peroxidase activities in anoxia-grown coleoptiles and roots recovered almost to the air-control levels. On exposure to ABA, the enhancement of coleoptile elongation and the decrease of cell wall-bound peroxidase activity in anoxia-grown coleoptiles were inhibited. These results indicate that there is a reciprocal correlation between growth and cell wall-bound peroxidase levels in etiolated rice seedlings.