Control of adventitious rooting and xylogenesis in arabidopsis

The Arabidopsis thaliana transcription factors SHORT ROOT (SHR) and SCARECROW (SCR) affect primary/lateral root development, as do the auxin-influx carriers LAX3 and AUX1. Della Rovere et al. study their involvement in adventitious root (AR) formation and xylogenesis using null-mutant seedlings grown with or without auxin-plus-cytokinin. They find that AR-formation and xylogenesis are developmental programmes that are inversely related, but which involve fine-tuning by the same proteins, namely SHR, SCR and AUX1. Pericycle activity is central for the equilibrium between xylary development and AR-formation in the hypocotyl, with a role for AUX1 in switching between, and balancing of, the two developmental programmes.