Fig. 7: CEP peptide and cytokinin pathways converge on CEPD glutaredoxins to inhibit root growth.

In the shoot, the perception of root-derived CEP by CEPR1 results in increased CEPD1,2 glutaredoxin production (red text). Shoot derived CEPD1,2 travels to the root via the phloem. In the root, tZ signals locally through AHK2,3 to transcriptionally induce local CEPD1 production (black text). It is possible that tZ signals through CEPD2 (grey text) locally via other mechanisms (e.g. post-translationally). The pool of shoot- and root-derived CEPD (orange box with broken lines) ultimately integrates root growth responses with whole-of-plant nutritional and environmental stress status. tZ trans-zeatin, AHK ARABIDOPSIS HISTIDINE KINASE, CEP C-TERMINALLY ENCODED PEPTIDE, CEPR CEP RECEPTOR, CEPD CEP DOWNSTREAM.