Root gravitropism allows plants to establish root systems and its regulation depends on polar auxin transport mediated by PIN-FORMED (PIN) auxin transporters. PINOID (PID) and PROTEIN PHOSPHATASE 2A (PP2A) act antagonistically on reversible phosphorylation of PINs. This regulates polar PIN distribution and auxin transport. Here we show that a peptidyl-prolyl cis/trans isomerase Pin1At regulates root gravitropism. Downregulation of Pin1At suppresses root agravitropic phenotypes of pp2aa and 35S:PID, while overexpression of Pin1At affects root gravitropic responses and enhances the pp2aa agravitropic phenotype. Pin1At also affects auxin transport and polar localization of PIN1 in stele cells, which is mediated by PID and PP2A. Furthermore, Pin1At catalyses the conformational change of the phosphorylated Ser/Thr-Pro motifs of PIN1. Thus, Pin1At mediates the conformational dynamics of PIN1 and affects PID- and PP2A-mediated regulation of PIN1 polar localization, which correlates with the regulation of root gravitropism.

中文翻译：

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Pin1At调节PIN1的极性定位和根向重力。

根重性使植物能够建立根系，其调控取决于由PIN-FORMED（PIN）生长素转运蛋白介导的极性植物生长素转运。PINOID（PID）和蛋白质磷酸酶2A（PP2A）对PIN的可逆磷酸化具有拮抗作用。这可调节极性PIN的分布和植物生长素的运输。在这里，我们显示肽基-脯氨酰顺/反异构酶Pin1At调节根向重力。Pin1At的下调抑制了pp2aa和35S：PID的根重力表型，而Pin1At的过表达影响根的重力反应并增强了pp2aa的重力表型。Pin1At还影响由PID和PP2A介导的石碑细胞中PIN1的生长素运输和极性定位。此外，Pin1At催化PIN1的磷酸化Ser / Thr-Pro基序的构象变化。因此，