Matches in UGent Biblio for { ?s ?p 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 Ca2+ levels. Pharmacological and genetic increases in InsP(3) or Ca2+ 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 Ca2+ signaling antagonized the effects of the supo1 mutation and disrupted preferentially apical PIN localization. InsP(3) 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.. }
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- aggregation 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 (InsP(3)) and cytosolic Ca2+ levels. Pharmacological and genetic increases in InsP(3) or Ca2+ 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 Ca2+ signaling antagonized the effects of the supo1 mutation and disrupted preferentially apical PIN localization. InsP(3) 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.".