Graphene Oxide as an Effective Soil Water Retention Agent Can Confer Drought Stress Tolerance to Paeonia ostii without Toxicity

Abstract

Graphene oxide (GO) is considered to be an emerging environmental pollutant with its inevitable release into the environment. Thus, its potential environmental risks and biosafety are receiving increased attention. In this study, Paeonia ostii was exposed to GO under drought stress. The results demonstrated that GO prevented soil water from evaporating due to its hydrophilic oxygen-containing functional groups and did not change the soil pH. Moreover, GO treatment resulted in lower increases in reactive oxygen species, relative electrical conductivity and free proline content, and greater increases in the antioxidant enzyme activities of P. ostii under drought stress compared with those in the control. And under drought stress, higher photosynthesis, more intact mesophyll cells and organelles and open stomata were found in P. ostii under GO treatment. Furthermore, GO treatment induced greater changes in the expression patterns of genes required for lignin biosynthesis, photosynthesis-antenna proteins, carbon fixation in photosynthetic organisms, and glyoxylate and dicarboxylate metabolism. Additionally, GO did not accumulate in P. ostii due to the soil environment and the electrostatic repulsion between GO and the roots. GO did not have toxic effects on P. ostii and was an effective soil water retention agent; therefore, it could be economically beneficial for the production of plants under drought stress.

Graphene Oxide, a Novel Nanomaterial as Soil Water Retention Agent, Dramatically Enhances Drought Stress Tolerance in Soybean Plants

“…In addition, the previous studies showed that the surface morphology and internal structure of Paeonia ostii roots were not obviously different between GO and without GO treatment using SEM and TEM. Raman spectroscopy detection also indicated the absence of GO in the cells of the Paeonia ostii roots ( Zhao et al, 2020 ). He et al (2018a) also confirmed that GO could not accumulate in Spinacia oleracea L. seedlings cultivated in the soil.…”

“…Graphene oxide (GO), a novel nanomaterial as a soil water retention agent, plays a role in the growth and development of plants ( Shen et al, 2018 ; Xie et al, 2020 ). GO not only increased the drought tolerance of in Zea mays L. and Paeonia ostii ( Zhao et al, 2020 ; Lopes et al, 2021 ), but also enhanced the saline-alkali tolerance of Medicago sativa L. ( Chen et al, 2021 ). In addition, the previous studies showed that the surface morphology and internal structure of Paeonia ostii roots were not obviously different between GO and without GO treatment using SEM and TEM.…”

“…However, relatively few studies have investigated the effect of GO on drought tolerance. Recently, it has been found that GO as an effective soil water retention agent can confer drought stress tolerance to Paeonia ostii without causing toxicity ( Zhao et al, 2020 ). Furthermore, the effects of GO nanosheets were in a drought context, with the osmotic and antioxidant protection conferred by GO nanosheets to drought shoots, leading to higher shoot biomass ( Lopes et al, 2021 ).…”

Effects of High-Temperature Stress on Photosynthetic Characteristics and Antioxidant Enzyme System of Paeonia ostii

“…Anatomical observation referred to our previous studies [17,22]. Fresh leaves were cut into sections of 3 × 3 cm with a blade and then fixed in 2.5% glutaraldehyde solution at 4°C for at least 4 h. Then, the fixed leaves were washed three times with 0.1 mol/L phosphate buffer for 15 min each and were then sequentially dehydrated in a gradient of ethanol solutions (30%, 50%, 70%, 80%, 90%, 95%, and 100% solutions) for 15 min each.…”

Selection of Stable Reference Genes for Quantitative Real-Time PCR on Paeonia ostii T. Hong et J. X. Zhang Leaves Exposed to Different Drought Stress Conditions

“…In our previous research, some drought stress-relevant indicators were measured, and we have tried to find useful ways to alleviate the drought stress of P. ostii [52,53]. At the same time, with the development of transcriptome sequencing, research on drought stress has gradually advanced and deepened from the physiological to the molecular level [54].…”