Polar auxin transport, mediated by the PIN-FORMED (PIN) class of auxin effl ux carriers, controls organ initiation in plants. In maize, BARREN INFLORESCENCE2 (BIF2) encodes a serine/threonine protein kinase co-orthologous to PINOID (PID), which regulates the subcellular localization of AtPIN1 in Arabidopsis. We show that BIF2 phosphorylates ZmPIN1a, a maize homolog of AtPIN1, in vitro and regulates ZmPIN1a subcellular localization in vivo, similar to the role of PID in Arabidopsis. In addition, bif2 mutant infl orescences have lower auxin levels later in development. We propose that BIF2 regulates auxin transport through direct regulation of ZmPIN1a during maize infl orescence development.
Bibliographical noteFunding Information:
The National Science Foundation (IBN-0416616 to P.M., DBI-0501862 to D.J., MCB-0643845, MCB-0725149 and DBI-0606666 to J.D.C.); a Cold Spring Harbor Laboratory Association Fellowship (to A.G.)
- Auxin transport
- Barren infl orescence2