A Novel Aux/IAA28 Signaling Cascade Activates GATA23-Dependent Specification of Lateral Root Founder Cell Identity

Bert De Rybel, Valya Vassileva, Boris Parizot, Marlies Demeulenaere, Wim Grunewald, Dominique Audenaert, Jelle Van Campenhout, Paul Overvoorde, Leentje Jansen, Steffen Vanneste, Barbara Möller, Michael Wilson, Tara Holman, Gert Van Isterdael, Géraldine Brunoud, Marnik Vuylsteke, Teva Vernoux, Lieven De Veylder, Dirk Inzé, Dolf Weijers, Malcolm J. Bennett & Tom Beeckman

Background

Lateral roots are formed at regular intervals along the main root by recurrent specification of founder cells. To date, the mechanism by which branching of the root system is controlled and founder cells become specified remains unknown.

Results

Our study reports the identification of the auxin regulatory components and their target gene, GATA23, which control lateral root founder cell specification. Initially, a meta-analysis of lateral root-related transcriptomic data identified the GATA23 transcription factor. GATA23 is expressed specifically in xylem pole pericycle cells before the first asymmetric division and is correlated with oscillating auxin signaling maxima in the basal meristem. Also, functional studies revealed that GATA23 controls lateral root founder cell identity. Finally, we show that an Aux/IAA28-dependent auxin signaling mechanism in the basal meristem controls GATA23 expression.

Conclusions

We have identified the first molecular components that control lateral root founder cell identity in the Arabidopsis root. These include an IAA28-dependent auxin signaling module in the basal meristem region that regulates GATA23 expression and thereby lateral root founder cell specification and root branching patterns.

Current Biology 20 (19), 1697-1706