Fig. 2.

Mechanism for provascular specification during embryo development. a Illustration of the localization of (1) the initial cells in the globular-stage embryo from which all vascular tissues originate and (2) the periclinal divisions that give rise to additional vascular cells in a heart-stage embryo. b Gene regulatory network that determines vascular cell identity and cell divisions during embryo development. In response to local accumulation of auxin, the MP auxin-dependent transcription factor enhances auxin accumulation through the upregulation of the PIN1 auxin transporter, establishes vascular identity by inducing the ATHB8 HD-ZIP III transcription factor, and promotes periclinal cell divisions via TMO5-LHW-mediated increase in CK synthesis