Condensed tannins as antioxidants that protect poplar against oxidative stress from drought and UV‐B

Condensed tannins (CTs, proanthocyanidins) are widespread polymeric flavan‐3‐ols known for their ability to bind proteins. In poplar (Populus spp.), leaf condensed tannins are induced by both biotic and abiotic stresses, suggesting diverse biological functions. Here we demonstrate the ability of CTs...

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Bibliographic Details
Published in:Plant, cell and environment cell and environment, 2022-02, Vol.45 (2), p.362-377
Main Authors: Gourlay, Geraldine, Hawkins, Barbara J., Albert, Andreas, Schnitzler, Jörg‐Peter, Peter Constabel, C.
Format: Article
Language:English
Subjects:
Abiotic stress
Antioxidants
Antioxidants - pharmacology
Chlorophyll
Drought
Droughts
flavan‐3‐ols
flavonoids
Fluorescence
Hydrogen peroxide
Irradiation
Malondialdehyde
Oxidative Stress
Photosystem II
plant physiology
Poplar
Populus
Populus - drug effects
Populus - physiology
Populus - radiation effects
proanthocyanidins
Proanthocyanidins - pharmacology
Radiation damage
reactive oxygen species
RNA-mediated interference
Tannins
Ultraviolet Rays - adverse effects
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Summary:Condensed tannins (CTs, proanthocyanidins) are widespread polymeric flavan‐3‐ols known for their ability to bind proteins. In poplar (Populus spp.), leaf condensed tannins are induced by both biotic and abiotic stresses, suggesting diverse biological functions. Here we demonstrate the ability of CTs to function as physiological antioxidants, preventing oxidative and cellular damage in response to drought and UV‐B irradiation. Chlorophyll fluorescence was used to monitor photosystem II performance, and both hydrogen peroxide and malondialdehyde content was assayed as a measure of oxidative damage. Transgenic MYB‐overexpressing poplar (Populus tremula × P. tremuloides) with high CT content showed reduced photosystem damage and lower hydrogen peroxide and malondialdehyde content after drought and UV‐B stress. This antioxidant effect of CT was observed using two different poplar MYB CT regulators, in multiple independent lines and different genetic backgrounds. Additionally, low‐CT MYB134‐RNAi transgenic poplars showed enhanced susceptibility to drought‐induced oxidative stress. UV‐B radiation had different impacts than drought on chlorophyll fluorescence, but all high‐CT poplar lines displayed reduced sensitivity to both stresses. Our data indicate that CTs are significant defences against oxidative stress. The broad distribution of CTs in forest systems that are exposed to diverse abiotic stresses suggests that these compounds have wider functional roles than previously realized.
ISSN:0140-7791
1365-3040
DOI:10.1111/pce.14242