Activity and expression of peroxidases from sunflower; Effect of development

M.D. GROPPA; M.L. TOMARO; M.E. FERNANDEZ

REVISTA BRASILEIRA DE FISIOLOGIA VEGETAL

Año: 1999 vol. 11 p. 55 - 59

0103-3131

Expression and activity of peroxidase (EC 1.11.1.7) isozymes from seeds, seedlings and plant tissues of sunflower (Helianthus annus L.) were investigated. Only anionic isozymes were found in 7,14 and 28-day-old plants. The isozyme patterns were tissue specific. Little changes were found in isozyme patterns as a function of time, except for cotyledons which were the only organs to become senescent throughout our study. Only cationic isozymes were found in seeds and seedlings up to the forth day after planting. Anionic isozymes began to appear from this day on and cationic isozymes began to disappear. This "switch" in isozyme expression was coincident wit the appearance of the root and with a change in susbstrate specificity. None of the extracts showed indoleacetic acid oxidase activity, not even a partially purified extract from seeds. A membrane bound peroxidase activator, active during the first and second day after planting, was found in seeds. the activation effect of the membranes was trypsin-sensitive and the activator could be partially solubilized from membranes with 1 % sodium cholate in 20 mM Tris buffer, pH 7.4.