AtCRY2 Negatively Regulates the Functions of AtANN2 and AtANN3 in Drought Tolerance by Affecting Their Subcellular Localization and Transmembrane Ca2+ Flow.

Ting Liu,Jingda Kang,Shilin Wang,Leyan Du,Qi Guo,Qiushi Li

doi:10.3389/fpls.2021.754567

Ting Liu, Jingda Kang + Show 4 more

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https://doi.org/10.3389/fpls.2021.754567

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Abstract

Annexins are a multifunctional class of calcium-binding proteins in plants, and their physiological functions and regulation in response to drought stress remain to be elucidated. Here, we found that AtANN2 and AtANN3 conferred to drought tolerance under short-day and long-day conditions, respectively. Under their functional photoperiod, AtANN2 and AtANN3 gene expression was enhanced in the mannitol-treated roots, and their encoded proteins were rapidly targeted to the plasma membrane, and mediated significant Ca2+ flows across the plasma membrane. Cryptochromes as photoreceptors can not only sense the photoperiod and regulate ion channels on the plasma membrane to influence ion flow but also induce downstream physiological responses. AtCRY2 repressed the functions of AtANN2 and AtANN3 by affecting their plasma membrane localization and inhibited AtANN2- and AtANN3-dependent transmembrane Ca2+ flow in response to drought stress. Taken together, these results uncover a mechanism linking Annexins-AtCRY2 to transmembrane Ca2+ flow and resulting in enhanced drought tolerance in Arabidopsis.

Highlights

Plant cells trigger a series of signal transduction pathways to regulate physiological responses to adapt to environmental changes (Bechtold, 2018; Gong et al, 2020; Lamers et al, 2020)
Annexins can act as sensors sensing calcium signals early in the environmental signaling pathway and trigger the generation of specific downstream calcium signals (Baucher et al, 2012)
The Quantitative real-time PCR analysis (qRT-PCR) analysis showed that the expression levels of AtANN2 and AtANN3 genes were completely disrupted in the null mutants atann2 and atann3, and were able to be recovered in the complementary lines AtANN2COM and AtANN3-COM to the same level as those in Col0

Summary

Introduction

Plant cells trigger a series of signal transduction pathways to regulate physiological responses to adapt to environmental changes (Bechtold, 2018; Gong et al, 2020; Lamers et al, 2020). An external signal is sensed by a sensor on the plasma membrane, and a second messenger is stimulated through transmembrane signal transduction to induce changes in the activity of functional proteins in the cell to regulate physiological responses. At the level of environmental regulators, annexins may be involved in the physiological responses of plants to adverse stress, such as metal stress (Tuomainen et al, 2010), cold stress (Liu et al, 2021), drought stress (Konopka-Postupolska et al, 2009), and salt stress (Ma et al, 2019)

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