TY - JOUR AB - The phytohormone auxin is an important determinant of plant development. Directional auxin flow within tissues depends on polar localization of PIN auxin transporters. To explore regulation of PIN-mediated auxin transport, we screened for suppressors of PIN1 overexpression (supo) and identified an inositol polyphosphate 1-phosphatase mutant (supo1), with elevated inositol trisphosphate (InsP 3) and cytosolic Ca 2+ levels. Pharmacological and genetic increases in InsP 3 or Ca 2+ levels also suppressed the PIN1 gain-of-function phenotypes and caused defects in basal PIN localization, auxin transport and auxin-mediated development. In contrast, the reductions in InsP 3 levels and Ca 2+ signaling antagonized the effects of the supo1 mutation and disrupted preferentially apical PIN localization. InsP 3 and Ca 2+ are evolutionarily conserved second messengers involved in various cellular functions, particularly stress responses. Our findings implicate them as modifiers of cell polarity and polar auxin transport, and highlight a potential integration point through which Ca 2+ signaling-related stimuli could influence auxin-mediated development. AU - Zhang, Jing AU - Vanneste, Steffen AU - Brewer, Philip B AU - Michniewicz, Marta AU - Peter Grones AU - Kleine-Vehn, Jürgen AU - Löfke, Christian AU - Teichmann, Thomas AU - Bielach, Agnieszka AU - Cannoot, Bernard AU - Hoyerová, Klára AU - Xu Chen AU - Xue, Hong-Wei AU - Eva Benková AU - Zažímalová, Eva AU - Jirí Friml ID - 3089 IS - 6 JF - Developmental Cell TI - Inositol trisphosphate-induced ca^2+ signaling modulates auxin transport and pin polarity VL - 20 ER -