Biotic and Abiotic Stresses Activate Different Ca2+ Permeable Channels in Arabidopsis.

Xiao-Qiang Cao,Zhen-Ming Pei,Shan Zhu,Zhong-Hao Jiang,Yi Yang,Yan-Yan Yi,Li-Ping Ke

doi:10.3389/fpls.2017.00083

Abstract

To survive, plants must respond rapidly and effectively to various stress factors, including biotic and abiotic stresses. Salinity stress triggers the increase of cytosolic free Ca2+ concentration ([Ca2+]i) via Ca2+ influx across the plasma membrane, as well as bacterial flg22 and plant endogenous peptide Pep1. However, the interaction between abiotic stress-induced [Ca2+]i increases and biotic stress-induced [Ca2+]i increases is still not clear. Employing an aequorin-based Ca2+ imaging assay, in this work, we investigated the [Ca2+]i changes in response to flg22, Pep1, and NaCl treatments in Arabidopsis thaliana. We observed an additive effect on the [Ca2+]i increase which induced by flg22, Pep1, and NaCl. Our results indicate that biotic and abiotic stresses may activate different Ca2+ permeable channels. Further, calcium signal induced by biotic and abiotic stresses was independent in terms of spatial and temporal patterning.

Highlights

In the natural environment, plants have to continuously cope with various stress factors, such as salt, drought, attacks of herbivorous insects, and invasion of microbial pathogens
We found that the increases of [Ca2+]i induced by both stimuli were higher than those induced by a single stress, suggesting that biotic and abiotic stresses have an additive effect on [Ca2+]i
To determine whether the mechanisms behind the increases of [Ca2+]i induced by biotic and abiotic stresses are interrelated in Arabidopsis, we first attempted to identify the optimum concentrations of flg22 and Pep1 that ideally could be applied to generate about half of the maximum amplitude of [Ca2+]i required for potential up- and down-regulation

Summary

Introduction

Plants have to continuously cope with various stress factors, such as salt, drought, attacks of herbivorous insects, and invasion of microbial pathogens. Plants should respond rapidly and effectively to each stressor. Recent studies revealed that about 10 million hectares of agricultural land are abandoned every year due to high salinity (Zhu, 2001, 2003; Munns and Tester, 2008). Plant diseases cause massive losses in agricultural yields as well as abiotic stresses (Singh et al, 2011; Dangl et al, 2013; Yoshida et al, 2013). The simultaneous occurrence of different stresses results in a high degree of complexity in terms of plant responses, as the responses to the combined stresses are largely controlled by different, and sometimes opposing, signaling pathways that may interact and inhibit each other (Suzuki et al, 2014). It is critical to study how plants respond to both biotic and abiotic stresses

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Conclusion