Myo-Inositol Esters of Indole-3-acetic Acid as Seed Auxin Precursors of Zea mays L

Indole-3-acetyl-myo-inositol esters constitute 30% of the low molecular weight derivatives of indole-3-acetic acid (IAA) in seeds of Zea mays. [¹⁴C]Indole-3-acetyl-myo-inositol was applied to a cut in the endosperm of the seed and found to be transported from endosperm to shoot at 400 times the rate of transport of free IAA. The rate of transport of indole-3-acetyl-myo-inositol from endosperm to shoot was 6.3 picomoles per shoot per hour and thus adequate to serve as the seed auxin precursor for the free IAA diffusing downward from the shoot tip. Indole-3-acetyl-myo-inositol is the first seed auxin precursor to be identified.