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Uncoupling of reactive oxygen species accumulation and defence signalling in the metal hyperaccumulator plant N occaea caerulescens
Author(s) -
Fones Helen N.,
Eyles Chris J.,
Bennett Mark H.,
Smith J. Andrew C.,
Preston Gail M.
Publication year - 2013
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.12354
Subject(s) - hyperaccumulator , reactive oxygen species , callose , pseudomonas syringae , salicylic acid , biology , defence mechanisms , microbiology and biotechnology , arabidopsis , oxidative stress , plant defense against herbivory , botany , biochemistry , pathogen , cell wall , gene , ecology , contamination , soil contamination , mutant
Summary The metal hyperaccumulator plant N occaea caerulescens is protected from disease by the accumulation of high concentrations of metals in its aerial tissues, which are toxic to many pathogens. As these metals can lead to the production of damaging reactive oxygen species ( ROS ), metal hyperaccumulator plants have developed highly effective ROS tolerance mechanisms, which might quench ROS ‐based signals. We therefore investigated whether metal accumulation alters defence signalling via ROS in this plant. We studied the effect of zinc ( Z n) accumulation by N . caerulescens on pathogen‐induced ROS production, salicylic acid accumulation and downstream defence responses, such as callose deposition and pathogenesis‐related ( PR ) gene expression, to the bacterial pathogen P seudomonas syringae pv. maculicola. The accumulation of Z n caused increased superoxide production in N . caerulescens , but inoculation with P . syringae did not elicit the defensive oxidative burst typical of most plants. Defences dependent on signalling through ROS (callose and PR gene expression) were also modified or absent in N . caerulescens , whereas salicylic acid production in response to infection was retained. These observations suggest that metal hyperaccumulation is incompatible with defence signalling through ROS and that, as metal hyperaccumulation became effective as a form of elemental defence, normal defence responses became progressively uncoupled from ROS signalling in N . caerulescens .