Auxin is a classic Phytohormone involved in a myriad of Developmental and Environmental Processes: Embryo Patterning, Cell Division and Elongation, Vascular Differentiation, Lateral Root Initiation, Gravitropism, and Phototropism. Though many natural and synthetic compounds exhibit Auxin-like activity in bioassays, IAA (Indole-3-Acetic Acid) is recognized as the key Auxin in most plants. IAA gene family consists of over 20 members in Arabidopsis. The physiologically active form is the free acid, but IAA can also be found in different conjugated forms, including Ester-types with the Carboxyl group linked via Oxygen to a Sugar (for example Glucose) and Amide-types with the Carboxyl group forming an Amide (Peptide bond) to Amino Acids or Polypeptides. Plants use several pathways to synthesize IAA but none of [...]