Review: Roles for IBA-derived auxin in plant development ($)

Auxin biosynthesis is a two-step process:  First, tryptophan is converted to indole-3-pyruvic acid (IPyA) through the activity of the TAA1 (TRYPTOPHAN AMINOTRANSFERASE OF ARABIDOPSIS1) family of aminotransferase enzymes. IPyA is finally converted to IAA (Indole Acetic Acid) by YUCCA family of flavin monooxygenase-like enzymes. Other than tryptophan, IAA is also produced from IBA (indole-3-butyric acid). IBA itself is not perceived by TIR/AFB receptors and IBA has been genetically shown to act through its conversion to IAA. In this review, Frick and Strader describe the mechanism of IBA conversion, transport, and role in shoot and root development, and outstanding quetions about IBA biology. J. Exp. Bot. 10.1093/jxb/erx298