The research explored how CeO2NPs, specifically poly (acrylic acid)-coated nanoceria (PNC), impacted salt tolerance in the salt-sensitive Huanghuazhan (H) and salt-tolerant Xiangliangyou900 (X).
Under salt stress, PNC-primed plants showed increased plant height, root length, and fresh weight compared to controls.
These findings suggest that PNC generally promotes growth and maintains photosynthetic efficiency under saline conditions.
The study found that PNC helped rice roots cope with salty conditions by boosting protective enzymes and reducing harmful molecules. It also activated natural antioxidant systems in the plant.
This suggested that they were a first shield against stress-related damage, protecting plants from stress-induced oxidative damage.
Methods
Seeds of both cultivars were “primed” with 100 mg L−1 PNC against control treatments for 48 hours.
“PNC priming can be absorbed by seeds at low doses, avoiding the risk of cerium residue that may be caused by high-dose spraying; moreover, the seed stage is a critical window for establishment of ROS homeostasis and hormone signalling; PNC priming can activate antioxidant signals at an early stage, enabling plants to mount a rapid defensive response when salt stress occurs,” said the study.
After germination, seedlings were exposed to salt stress with 50 mM NaCl solution for 7 days.
The plants were then measured for agronomic traits such as plant height, root length, and fresh weight.
The experiment also observed photosynthetic parameters, reactive oxygen species (ROS) levels, antioxidant enzyme activities, and endogenous hormone levels.
Same PNCs, different mechanisms
The study noted that China had the world’s third-largest area of saline land, making it a pressing issue
“Soil salinity has become an environmental problem globally due to climate change, fertilizer and pesticide misuse, and irrational irrigation by humans, affecting plant growth and development.”
While previous studies have shown that CeO2NPs can boost salt tolerance in various crops, including rice, the detailed mechanisms have been unclear.
Interestingly, the underlying mechanism of how the PNC helped the plants to achieve salt tolerance were significantly differently between H and X.
In the salt-sensitive H cultivar, the enhanced tolerance was “primarily attributed to enhanced photosynthesis”, with net photosynthesis and transpiration rates were 53.27% and 20.52% higher than the X cultivar.
With the salt-tolerant X variety, PNC enhanced salt tolerance by activating cellular defence responses and boosting protective enzymes.
It also helped produce proline and glutathione, which protect cells from damage, as well as raised growth hormone levels.
Lastly, the research noted how PNC switched on certain stress-response genes, further boosting its ability to adapt to the salt environment.
The results of this study provided “new insights and revelations for the genetic improvement of salt-tolerant rice cultivars”
Source: Antioxidants
An Analysis of the Different Salt-Tolerance Mechanisms in Rice Cultivars Induced by Cerium Oxide Nanoparticles
Authors: Chunmei Yang et al.
https://doi.org/10.3390/antiox14080994