Root branching toward water involves posttranslational modification of transcription factor ARF7 ($) (Science)

Roots do amazing things, particularly in terms of how they optimize their growth in response to their very local environment including water, nutrients, microbes, and physical obstructions. Branching in regions of contact with water is called hydropatterning, and previous studies showed that an auxin gradient forms in response to differential water contact. Orosa-Puente, Leftley, von Wangenheim et al. now show that the transcription factor ARF7 is also involved, and its action is mediated in part by one of its transcriptional targets, LBD16. Their study finds that on the wet side of the root, ARF7 is active and promotes lateral root formation, whereas on the dry side ARF7 is posttranslationally modified through SUMOylation, promoting interaction with the IAA3 repressor protein. (Summary by Mary Williams)  Science 10.1126/science.aau3956