The xerobranching response represses lateral root formation when roots are not in contact with water (Curr. Biol. – $)

Roots navigate through the soil, foraging for water and nutrients. Orman-Ligeza et al. observed that lateral root development is repressed when the roots are growing through the soil air spaces. Exposure to water deficit induced transcriptome reprogramming in barley roots of genes involved in many hormone pathways. The reduced lateral root formation was also occurring in roots transiently exposed to abscisic acid (ABA), while ABA-insensitive mutants did not show changes in lateral root formation. By using auxin reporters, the authors discovered that reduced lateral root formation is due to decreased auxin levels at the root tip resulting in reduced initiation of the lateral root founder cells. Treatment of the roots with auxin restored lateral root development. How ABA modulates auxin accumulation remains to be determined in future studies. (Summary by Magdalena Julkowska) Curr. Biol. 10.1016/j.cub.2018.07.074