A second experiment was performed to study the effects of a prolonged (9 days) exposure to A.ovalisporum cell extracts. Fresh weight and dry weight of rice roots and leaves were measured from the third day. A significant decrease in leaf fresh weight of leaves in the nineth day of the exposure was detected, indicating a loss of water content in the cells (Fig. 4b). In addition, visual changes were observed. The leaves were browning with loss of green color and loss of extension from the sixth day since the exposure. The activities of GST increased in roots of the 9-day exposed plants and in leaves of the 3-day exposed plants (Fig. 5a). On the other hand, significant increases in GPx were registered in roots of the 6-day and 9-day exposed plants (Fig. 5b).