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Mechanisms of glacial‐to‐future atmospheric CO 2 effects on plant immunity
Author(s) -
Williams Alex,
Pétriacq Pierre,
Schwarzenbacher Roland E.,
Beerling David J.,
Ton Jurriaan
Publication year - 2018
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.15018
Subject(s) - jasmonic acid , plant immunity , nadph oxidase , biology , arabidopsis , plant disease resistance , photorespiration , mutant , reactive oxygen species , salicylic acid , microbiology and biotechnology , chemistry , biochemistry , genetics , gene , enzyme
Summary The impacts of rising atmospheric CO 2 concentrations on plant disease have received increasing attention, but with little consensus emerging on the direct mechanisms by which CO 2 shapes plant immunity. Furthermore, the impact of sub‐ambient CO 2 concentrations, which plants have experienced repeatedly over the past 800 000 yr, has been largely overlooked. A combination of gene expression analysis, phenotypic characterisation of mutants and mass spectrometry‐based metabolic profiling was used to determine development‐independent effects of sub‐ambient CO 2 ( sa CO 2 ) and elevated CO 2 ( e CO 2 ) on Arabidopsis immunity. Resistance to the necrotrophic Plectosphaerella cucumerina ( Pc ) was repressed at sa CO 2 and enhanced at e CO 2 . This CO 2 ‐dependent resistance was associated with priming of jasmonic acid ( JA )‐dependent gene expression and required intact JA biosynthesis and signalling. Resistance to the biotrophic oomycete Hyaloperonospora arabidopsidis ( Hpa ) increased at both e CO 2 and sa CO 2 . Although e CO 2 primed salicylic acid ( SA )‐dependent gene expression, mutations affecting SA signalling only partially suppressed Hpa resistance at e CO 2 , suggesting additional mechanisms are involved. Induced production of intracellular reactive oxygen species ( ROS ) at sa CO 2 corresponded to a loss of resistance in glycolate oxidase mutants and increased transcription of the peroxisomal catalase gene CAT 2 , unveiling a mechanism by which photorespiration‐derived ROS determined Hpa resistance at sa CO 2 . By separating indirect developmental impacts from direct immunological effects, we uncover distinct mechanisms by which CO 2 shapes plant immunity and discuss their evolutionary significance.