1. Laboratory of Plant Physiology, Kasteelpark Arenberg 31, Laboratory of Physiology and Immunology of Domestic Animals, Kasteelpark Arenberg 30, and Laboratory of Organic Synthesis, Celestijnenlaan 200F, Katholieke Universiteit Leuven, B-3001 Leuven, Belgium, and UNESP, Jaboticabal, Capes, Brazil