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Adv Sci (Weinh). 2019 Dec 11;7(3):1901455. doi: 10.1002/advs.201901455. eCollection 2020 Feb.

Root Growth Adaptation is Mediated by PYLs ABA Receptor-PP2A Protein Phosphatase Complex.

Author information

1
State Key Laboratory of Plant Physiology and BiochemistryCollege of Biological Sciences China Agricultural University Beijing 100193 China.
2
Institute of Science and Technology Austria Am Campus 1 3400 Klosterneuburg Austria.
3
State Key Laboratory of Crop Genetics and Germplasm Enhancement and MOA Key Laboratory of Plant Nutrition and Fertilization in Lower-Middle Reaches of the Yangtze River Nanjing Agricultural University Nanjing 210095 China.

Abstract

Plant root architecture dynamically adapts to various environmental conditions, such as salt-containing soil. The phytohormone abscisic acid (ABA) is involved among others also in these developmental adaptations, but the underlying molecular mechanism remains elusive. Here, a novel branch of the ABA signaling pathway in Arabidopsis involving PYR/PYL/RCAR (abbreviated as PYLs) receptor-protein phosphatase 2A (PP2A) complex that acts in parallel to the canonical PYLs-protein phosphatase 2C (PP2C) mechanism is identified. The PYLs-PP2A signaling modulates root gravitropism and lateral root formation through regulating phytohormone auxin transport. In optimal conditions, PYLs ABA receptor interacts with the catalytic subunits of PP2A, increasing their phosphatase activity and thus counteracting PINOID (PID) kinase-mediated phosphorylation of PIN-FORMED (PIN) auxin transporters. By contrast, in salt and osmotic stress conditions, ABA binds to PYLs, inhibiting the PP2A activity, which leads to increased PIN phosphorylation and consequently modulated directional auxin transport leading to adapted root architecture. This work reveals an adaptive mechanism that may flexibly adjust plant root growth to withstand saline and osmotic stresses. It occurs via the cross-talk between the stress hormone ABA and the versatile developmental regulator auxin.

KEYWORDS:

Arabidopsis; PIN phosphorylation; PP2A; PYLs; root adaptation

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