Regulation of the activity of adenylate cyclases by hydrogen peroxide in pea root cells Infected with pathogens and a mutualist

O V Kuzakova,L A Lomovatskaya,A M Goncharova,A S Romanenko

doi:10.21285/2227-2925-2020-10-3-450-458

Abstract

This study examines the effect of a range of exogenous concentrations of hydrogen peroxide on the activity of transmembrane and soluble adenylate cyclases (EC 4.6.1.1) contained in root cells of pea seedlings infected with one of the following: Rhizobium leguminosarum bv. Viciae, Pseudomonas syringae pv. Pisi, and Clavibacter michiganensis ssp. sepedonicus. The results showed that the pool of intracellular H2O2 increased when pea roots were infected with bacteria regardless of type. The study analysed the concentration of intracellular cyclic adenosine monophosphate, a product of the adenosine triphosphate cyclization reaction catalyzed by transmembrane and soluble adenylate cyclases. The concentration of intracellular cyclic adenosine monophosphate increased when infected with either Rhizobium leguminosarum bv. viciae or Clavibacter michiganensis ssp. Sepedonicus; however, the concentration decreased by 20% when infected with Pseudomonas syringae pv. Pisi. The in vitro activity of soluble and transmembrane adenylate cyclases from pea root cells inoculated with Rhizobium leguminosarum bv. viciae was H2O2 dose-dependent: 100 nM of H2O2 reduced the activity of soluble and transmembrane adenylate cyclases slightly, while 26 µM inhibited their activity by 50–60%. When infected with Pseudomonas syringae pv. pisi, the reduction in the activity of soluble and transmembrane adenylate cyclases was independent of the concentrations of H2O2 in the range investigated. When infected with Clavibacter michiganensis ssp. sepedonicus, 100 nM of H2O2 inhibited the activity of transmembrane adenylate cyclases, although enhancing the activity of soluble adenylate cyclases. On the contrary, concentrations of H2O2 of 2.6 and 26 µM increased the activity of transmembrane adenylate cyclases and inhibited the activity of soluble adenylate cyclases. It can be concluded that the specific concentration of second messengers in plant cells depends on the specificity of the biotic stressor and forms, inter alia, by their mutual influence on the components of other plant signaling systems.

Highlights

Second messengers of signaling systems participate in the regulation of plant metabolism at all stages of development and are subject to the influence of external agents, for example in biotic stress
We showed that the degree of activity of cyclic adenosine monophosphate and adenylate cyclase in root cells changed significantly 5 minutes after infection of the root of pea seedling with various agents [1, 3], viz. different strains of Rhizobium leguminosarum bv. viciae (Rlv) and phytopathogenic bacteria which differ by specialization, Pseudomonas syringae bv. pisi (Psp), the pathogen of peas, and Clavibacter michiganensis sps. sepedonicus (Cms), a specific pathogen for potato
The endogenous concentration of H2O2 and cyclic adenosine monophosphate (cAMP) in the root of a pea seedling infected with a mutualist and pathogens

Summary

Introduction

Second messengers of signaling systems participate in the regulation of plant metabolism at all stages of development and are subject to the influence of external agents, for example in biotic stress. Possible mechanisms for modulating the activity of both forms of adenylate cyclases (ACs) under biotic stress may include both ligand-receptor interactions [4] and the influence of calcium ions [5] The latter can act as an intracellular second messenger, and its concentration can change rapidly following infection. It should be noted that, in the early stages of biotic stress, the concentration of H2O2, another signal molecule, has already rapidly and sharply increased in the apoplast and intracellular space of plant cells [6,7,8], which is likely to cause analagous changes in the activity of both forms of ACs. knowledge of the effect of H2O2 molecules on the activity of transmembrane and soluble forms of AC in plant cells is isolated to specific examples and incomplete: for example, it was shown that 0.2–0.6 μM of H2O2 had only a minor effect on TACs and SACs from the vacuoles of beetroot parenchyma cells during various periods of root crop dormancy under long-term biotic stress [9]. The purpose of this study was to investigate the effect of the second messenger in the superoxide synthase signaling system (H2O2) on the activity of transmembrane and soluble forms of AC from pea root cells following inoculation with Rlv, Psp, and Cms

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