Effective
removal of excess reactive oxygen species (ROS) from
plants is important to minimize biotic and abiotic stress and increase
crop yield. Efficient natural ROS scavenging enzymes already exist;
however, these enzymes are sensitive to environmental conditions,
and it is challenging to produce them on a large scale. In this study,
using biomass Salvia miltiorrhiza as
the precursor, fluorescence carbon dots (CDs) were synthesized on
a large scale using a one-step hydrothermal method. After a series
of structural changes, the surface of CDs contains a S. miltiorrhiza-like polymer, which endows the CDs
with high antioxidant capacity. These CDs have multiple enzyme activities
with stronger antioxidant activity than that of the pure S. miltiorrhiza extract. CDs can scavenge DPPH•, O2
•–, and •OH with excellent
scavenging efficiencies of 88.9, 95.6, and 71.4%, respectively. Additionally,
the corresponding enzyme activities are superior to those of the natural
antioxidant Vc. The synthesized CDs not only have a good scavenging
effect on intracellular ROS in plants but can also effectively alleviate
the oxidative damage of Italian lettuce under salt stress. Compared
with the control group, the root and leaf biomass of Italian lettuce
significantly increased by 52.2 and 58.1%, respectively, the water
content increased by 48.2%, and malondialdehyde (MDA) content decreased
by 92.2%. This study provides a promising strategy for engineering
biological antioxidant systems with multiple enzyme activities to
attenuate plant biotic stress and abiotic stress.
As a multifunctional material, biochar is considered a potential adsorbent for removing heavy metals from wastewater. Most biochars with high adsorption capacities have been modified, but this modification is uneconomical, and modifying biochar may cause secondary pollution. Thus, it is necessary to develop an efficient biochar without modification. In this study, spent P. ostreatus substrate and spent shiitake substrate were used as the raw materials to prepare biochar. Then, the physicochemical properties of the biochars and their removal efficiencies for Pb(II) were investigated. The results showed that the physicochemical properties (e.g., large BET surface area, small pore structure and abundant functional groups) contributed to the large adsorption capacity for Pb(II); the maximum adsorption capacities were 326 mg g−1 (spent P. ostreatus substrate-derived biochar) and 398 mg g−1 (spent shiitake substrate-derived biochar), which are 1.6–10 times larger than those of other modified biochars. The Pb(II) adsorption data could be well described by the pseudo-second-order kinetic model and the Langmuir model. This study provides a new method to comprehensively utilize spent mushroom substrates for the sustainable development of the edible mushroom industry.
The
regulation of plant growth and developmental processes by carbon
dots (CDs) has been frequently reported. However, little is known
about how CDs are related to the yield and nutritional quality. In
this study, carbon dots, obtained by the hydrothermal method with l-cysteine and glucose, were systematically characterized and
applied to lettuces and tomatoes in a hydroponic nutrient solution
to comprehensively investigate the mechanism of regulation of plant
development by CDs. We found that CDs could accelerate seed germination,
promote root and hypocotyl elongation of seedlings by activating the
expression of genes encoding aquaporin proteins, and enhance the yield
and nutritional qualities of mature plants by promoting the absorption
of mineral elements together with the enhancement of photosynthesis.
These results provide systematic insights into the mechanisms by which
CDs regulate plant development.
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