Root xylem formation and vascular acclimation to water deficit involves endodermal ABA signaling via miR166 ($) (Development)

Abiotic stress influences plant development, with the phytohormone ABA playing an important role. Ramachandran et al. have demonstrated ABA mediated activation of microRNA 166, which regulates expression levels of the HD-ZIP III transcriptional factor family. Exogenously supplied ABA alters xylem patterning due to a change in cell fate, as demonstrated using xylem cell-type specific markers. Previous work has shown that miR166 acts in a gradient from the endodermis towards the center of root stele and this study suggests that such non-cell autonomous signaling could be influenced by ABA levels. In addition to exogenous ABA treatment assays, the plants were subjected to water deficit condition, which causes an increase in endogenous ABA levels. Under this drought-like condition a similar change in xylem patterning was observed. These results suggests that ABA can influence root xylem architecture by altering miR166 and HD-ZIP III levels. (Summary by Suresh Damodaran) Development  10.1242/dev.159202