Zhang J., Vanneste S., Brewer P.B., Michniewicz M., Grones P., Kleine-Vehn J., Lofke C., Teichmann T., Bielach A., Cannoot B., Hoyerova K., Chen X., Xue H-W., Benkova E., Zazimalova E., Friml J.
DEVELOPMENTAL CELL 20: 855-866, 2011

Keywords: auxin transport, PIN polarity
Abstract: 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 (InsP3) and cytosolic Ca2+ levels. Pharmacological and genetic increases in InsP3 or Ca2+ levels also suppressed the PIN1 gain-of-function phenotypes and caused defects in basal PIN localization, auxin transport and auxinmediated development. In contrast, the reductions in InsP3 levels and Ca2+ signaling antagonized the effects of the supo1 mutation and disrupted preferentially apical PIN localization. InsP3 and Ca2+ 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 Ca2+ signaling-related stimuli could influence auxin-mediated development.
DOI: IEB authors: Klára Hoyerová, Eva Zažímalová