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Anionic Cerium Oxide Nanoparticles Protect Plant Photosynthesis from Abiotic Stress by Scavenging Reactive Oxygen Species
journal contribution
posted on 2017-11-03, 00:00 authored by Honghong Wu, Nicholas Tito, Juan P. GiraldoPlant
abiotic stress leads to accumulation of reactive oxygen species
(ROS) and a consequent decrease in photosynthetic performance. We
demonstrate that a plant nanobionics approach of localizing negatively
charged, sub-11 nm, spherical cerium oxide nanoparticles (nanoceria)
inside chloroplasts in vivo augments ROS scavenging
and photosynthesis of Arabidopsis thaliana plants under excess light (2000 μmol m–2 s–1, 1.5 h), heat (35 °C, 2.5 h), and dark
chilling (4 °C, 5 days). Poly(acrylic acid) nanoceria (PNC) with
a hydrodynamic diameter (10.3 nm)lower than the maximum plant
cell wall porosityand negative ζ-potential (−16.9
mV) exhibit significantly higher colocalization (46%) with chloroplasts
in leaf mesophyll cells than aminated nanoceria (ANC) (27%) of similar
size (12.6 nm) but positive charge (9.7 mV). Nanoceria are transported
into chloroplasts via nonendocytic pathways, influenced
by the electrochemical gradient of the plasma membrane potential.
PNC with a low Ce3+/Ce4+ ratio (35.0%) reduce
leaf ROS levels by 52%, including hydrogen peroxide, superoxide anion,
and hydroxyl radicals. For the latter ROS, there is no known plant
enzyme scavenger. Plants embedded with these PNC that were exposed
to abiotic stress exhibit an increase up to 19% in quantum yield of
photosystem II, 67% in carbon assimilation rates, and 61% in Rubisco
carboxylation rates relative to plants without nanoparticles. In contrast,
PNC with high Ce3+/Ce4+ ratio (60.8%) increase
overall leaf ROS levels and do not protect photosynthesis from oxidative
damage during abiotic stress. This study demonstrates that anionic,
spherical, sub-11 nm PNC with low Ce3+/Ce4+ ratio
can act as a tool to study the impact of oxidative stress on plant
photosynthesis and to protect plants from abiotic stress.
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ratioleaf mesophyll cellsScavenging Reactive Oxygen Species Plant abiotic stresschloroplastvivo augments ROSabiotic stress exhibitplant nanobionics approachnanoceriaANCcerium oxide nanoparticlesplant enzyme scavengerleaf ROS levelsArabidopsis thaliana plantsphotosynthesisreactive oxygen speciesRubisco carboxylation ratessub -11 nm PNCAnionic Cerium Oxide Nanoparticles Protect Plant Photosynthesisabiotic stresscarbon assimilation ratessub -11 nmII
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