Comparative Study on the Effects of Silicon Nanoparticles and Cellulose Nanocrystals on Drought Tolerance in Tall Fescue (Festuca arundinacea Schreb.)

Abstract

Tall fescue (Festuca arundinacea Schreb.) is a herbaceous species that is commonly used for ecological slope restoration in China. However, water scarcity often constrains its growth due to the unique site conditions of steep slopes and climate-induced drought stress. This study aims to compare the ameliorative effects of silicon nanoparticles (Si NPs) and cellulose nanocrystals (CNCs) on drought stress in tall fescue and to elucidate their underlying mechanisms of action. The results indicated that drought stress impaired photosynthesis, restricted nutrient absorption, and increased oxidative stress, ultimately reducing biomass. However, Si NPs and CNCs enhanced drought tolerance and promoted biomass accumulation by improving photosynthesis, osmotic regulation, and antioxidant defense mechanisms. Specifically, Si NP treatment increased biomass by 48.71% compared to drought-stressed control plants, while CNCs resulted in a 33.41% increase. Transcriptome sequencing further revealed that both nanomaterials enhanced drought tolerance by upregulating genes associated with photosynthesis and antioxidant defense. Additionally, Si NPs improved drought tolerance by stimulating root growth, enhancing nutrient uptake, and improving leaf structure. In contrast, CNCs play a distinct role by regulating the expression of genes related to cell wall synthesis and metabolism. These findings highlight the crucial roles of these two nanomaterials in plant stress protection and offer a sustainable strategy for the maintenance and management of slope vegetation.

Keywords: cellulose nanocrystals; drought stress; silicon nanoparticles; slope; tall fescue; transcriptome.

Figure 1

Structure and chemical characterization of two nanomaterials: (A) transmission electron microscope (TEM) image of Si NPs, (B) TEM image of CNCs, (C) Fourier transform infrared spectroscopy (FTIR) comparison of Si NPs and CNCs, (D) X-ray diffraction (XRD) pattern of Si NPs, and (E) XRD pattern of CNCs.

Figure 2

Effects of Si NP and CNC application on the growth of tall fescue under drought stress: (A) phenotypic comparison of different treatment groups, (B) plant height, (C) leaf length, (D) leaf width, (E) stem diameter, (F) root length, and (G) biomass. Data are presented as mean ± standard deviation from three biological experiments. Different letters above the bars indicate significant differences among treatments based on Tukey’s HSD test (one-way ANOVA, p < 0.05). Treatment abbreviations: CK (control, well-watered), Si NPs (well-watered + 300 mg/L silicon nanoparticles), CNCs (well-watered + 100 mg/L cellulose nanocrystals), DS (drought stress), DS_Si NPs (drought stress + 300 mg/L silicon nanoparticles), DS_CNCs (drought stress + 100 mg/L cellulose nanocrystals).

Figure 3

Effects of Si NPs and CNCs on photosynthetic pigment content and gas exchange parameters in tall fescue leaves under drought stress: (A) chlorophyll a, (B) chlorophyll b, (C) carotenoids, (D) photosynthetic rate, (E) transpiration rate, (F) stomatal conductance. Data are presented as means ± standard deviation from three biological experiments. Different letters above the bars indicate significant differences among treatments based on Tukey’s HSD test (one-way ANOVA, p < 0.05). Treatment abbreviations: CK (control, well-watered), Si NPs (well-watered + 300 mg/L silicon nanoparticles), CNCs (well-watered + 100 mg/L cellulose nanocrystals), DS (drought stress), DS_Si NPs (drought stress + 300 mg/L silicon nanoparticles), DS_CNCs (drought stress + 100 mg/L cellulose nanocrystals).

Figure 4

Anatomical images of tall fescue leaves treated with Si NPs and CNCs under drought stress: (A) CK, (B) Si NPs, (C) CNCs, (D) DS, (E) DS_Si NPs, (F) DS_CNCs.

Figure 5

Effects of Si NPs and CNCs on malondialdehyde, osmotic regulators, and antioxidant enzyme activities in tall fescue leaves under drought stress: (A) malondialdehyde (MDA), (B) soluble protein, (C) soluble sugar, (D) proline, (E) catalase (CAT), (F) superoxide dismutase (SOD), (G) peroxidase (POD), (H) ascorbate peroxidase (APX), (I) glutathione reductase (GR). Data are presented as means ± standard deviation from three biological experiments. Different letters above the bars indicate significant differences among treatments based on Tukey’s HSD test (one-way ANOVA, p < 0.05). Treatment abbreviations: CK (control, well-watered), Si NPs (well-watered + 300 mg/L silicon nanoparticles), CNCs (well-watered + 100 mg/L cellulose nanocrystals), DS (drought stress), DS_Si NPs (drought stress + 300 mg/L silicon nanoparticles), DS_CNCs (drought stress + 100 mg/L cellulose nanocrystals).

Figure 6

Transcriptome analysis of plants sprayed with nanomaterials and control plants under normal water conditions. (A) Number of DEGs, (B) GO enrichment analysis of 1428 DEGs shared after the application of nanomaterials, (C) KEGG enrichment analysis of 1428 DEGs shared after the application of nanomaterials, (D) Venn analysis of DEGs after the application of nanomaterials. Treatment abbreviations: CK (control, well-watered), Si NPs (well-watered + 300 mg/L silicon nanoparticles), CNCs (well-watered + 100 mg/L cellulose nanocrystals).

Figure 7

Transcriptome analysis of plants sprayed with nanomaterials and control plants under drought stress. (A) Venn analysis of DEGs after the application of nanomaterials under drought stress, (B) GO enrichment analysis of 1389 shared DEGs under drought stress after the application of nanomaterials, (C) KEGG enrichment analysis of 1389 shared DEGs under drought stress after the application of nanomaterials. Treatment abbreviations: DS (drought stress), DS_Si NPs (drought stress + 300 mg/L silicon nanoparticles), DS_CNCs (drought stress + 100 mg/L cellulose nanocrystals).