Abstract
Nanoparticles (NPs) have a critical function in mitigating the disease of fruits and vegetables. In the present investigation, the effects of three levels of concentrations (0.05, 0.10, and 0.20 mg/mL) of titanium dioxide NPs (TiO2-NPs) and silicon dioxide NPs (SiO2-NPs) were investigated against fungus Phomopsis vexans, bacterium Ralstonia solanacearum, and Meloidogyne incognita (root-knot nematode). The present investigation’s findings found that the application of SiO2-NPs was more efficient against test pathogens in comparison to TiO2-NPs. The best result produced by SiO2-NPs against pathogenic strain was used in the molecular docking investigation with the protein of R. solanacearum to better understand the interaction of active amino acids with SiO2-NPs. The obtained results revealed that the administration of 0.20 mg/mL foliar spray of SiO2-NPs in plants with M. incognita improves up to 37.92% of shoot dry weight and increases 70.42% of chlorophyll content. P. vexans growth was suppressed by 41.2% with 0.62 mm of inhibition zone when SiO2-NPs were given at a dosage of 0.20 mg/mL. The reductions in egg hatching and M. incognita (J2) mortality were greater in SiO2-NPs than in TiO2-NPs. The results of scanning electron microscopy confirmed that the application of both NPs harmed test pathogens. The confocal study also showed the penetration of NPs among test pathogens.
1 Introduction
In the last decade, the human population is increasing day by day at the global level; it is expected that will be populated by 10 billion by 2050 and 800 million people will be facing a hunger situation by the year 2030 [1]. Thus, with the increasing population, it is needed to increase the production of the agriculture sector worldwide to achieve zero hunger. Around 4,100 plant-parasitic nematode species are responsible to cause diseases in agriculturally important plants and cause yield loss of around $US157 billion per year worldwide [2,3]. Generally, to control these diseases in plants, chemical pesticides are used on a large scale in the agriculture sector. The use of chemical pesticides can cause risks to human health and the environment through bioaccumulation and eutrophication. To overcome this problem, there is a need to find out alternatives to chemical pesticides for disease management in plants.
Recently, the demands for the use of nanotechnology in the agriculture sector have been rapidly increased to increase food production by avoiding the use of chemical pesticides for plant disease management.
Nanotechnology is an innovative scientific approach to developing materials at the nanoscale to take forward the agro-food sector with promising new tools and technology to increase food safety and security by protecting plants from pests and microbes. Nano, a Greek word that means dwarf, and materials with a range of 1–100 nm or 1.0 × 10−9 m are known as nanoparticles (NPs) and they have unique properties, which are absent in bulk material [4,5]. Nanotechnology could provide a diverse way in agriculture, such as the production of nano-fertilizers, nano-pesticides, nano-nutrients, nanocides, and nano-herbicides, and it starts a new era as agro-nanotechnology [6,7]. They have the potential to boost the plant metabolism, could stimulate seed germination, and induce defense against pests and pathogens [8,9]. NP, such as silicon (Si), is generally known for its beneficial effects on plants’ growth and physiological activities. It has the potential to mitigate the biotic stress in plants and induce the defense in plants against pathogens, such as fungi, bacteria, viruses, and nematodes, by reducing pathogen colonization and by inducing resistance [10,11]. The antimicrobial efficiency of the Si can be due to its induction of defense gene expression, which is related to pathogen-related proteins, hypersensitivity responses, and antimicrobial compound synthesis [12,13]. The nano-SiO2 is also used in the agriculture sector to develop the nano-fertilizers to improve the seed efficiency for germination with protection against several types of pathogens in plants [14]. Moreover, the titanium dioxide NPs (TiO2-NPs) are also used in the agriculture sector as an alternative to chemical pesticides for plant disease management and promote plant growth due to increasing antimicrobial activity against plant pathogens and reducing ecological toxicity [15,16]. This might be possible due to the strong oxidation reaction of titanium dioxide (TiO2) against organic compounds. However, the field application of NPs in plant disease management has not been properly investigated yet. The current investigation aimed to examine the effects of three levels of concentrations (0.05, 0.10, and 0.20 mg/mL) of TiO2-NPs and silicon dioxide NPs (SiO2-NPs) in the disease management of eggplants. The study also explores the antimicrobial activity of NPs against microbial strains, i.e., fungus Phomopsis vexans, bacterium Ralstonia solanacearum, and Meloidogyne incognita (root-knot nematode) of eggplants. Furthermore, molecular docking of SiO2-NPs against R. solanacearum protein was performed to determine amino acid interactions with NPs to better understand the mechanistic approach to control the propagation of pathogenic strain.
2 Materials and methods
2.1 Experimental setup
Eggplant seeds (CV. Navkiran) were surface sterilized (3.5 kg of soil in clay pots with 30-cm diameter) as described in our previous study [17]. In this experiment, sandy loam soil was used and gathered from the field of the Botany Department, Aligarh Muslim University, India. Inoculation of pathogens and sterilization of soil were also done as explained in our previous study [17]. After being inoculated, jars were kept at 30°C on a glasshouse bench. Five replicates for each treatment were used. Every day, 200 mL of water was added to each pot.
2.2 NPs’ preparation
The SiO2 nanopowder (particle size 5–15 nm, spherical, porous, product number 637246-50G) and TiO2-NPs (product number 700347-25G, a mixture of rutile and anatase, particle size <150 nm) were bought from Sigma Aldrich (USA). Spraying of SiO2-NPs/TiO2-NPs with three levels of strengths (0.05, 0.10, and 0.20 mg/mL) each was done on 10-day-old seedlings. Suspension of 0.05, 0.10, and 0.20 mg of these NPs is prepared by dissolving NPs in 1 mL of distilled water and sonicated for 25–30 min for equal distribution of NPs in water.
2.3 Confocal microscopy and scanning electron microscopic study
Nanoparticles effect on R. solanacearum cells, M. incognita and P. vexans hyphae morphological was investigated using Scanning Electron Microscopic (SEM). The SEM was performed after the second-stage juveniles of M. incognita were treated with SiO2- and TiO2-NP suspensions. After being exposed to NPs, J2s were fixed with glutaraldehyde at 40°C for 12 h. After fixing, J2s were dehydrated using an ethanol series treatment for 15 min for each concentration (10, 20, 40, 60, 80, 90, and 100%). Thereafter, J2s were mounted on gold-coated stubs and, finally, J2s were observed under SEM. The R. solanacearum cells were centrifuged at 5,000 rpm for 15 min at 4°C and the pellets were collected and rinsed with potassium phosphate-buffered saline (PBS) at pH 7. After that, the sample was fixed for 5–6 h with 2.5% glutaraldehyde. An ethanol series (10, 20, 40, 60, 80, 90, and 100%) was used to dehydrate the samples for 15 min each. Following that, the samples were subjected to SEM analysis (JEOL, Tokyo, Japan). The mycelium of P. vexans was fixed for 3–4 h with 2.5% glutaraldehyde and then washed with potassium phosphate buffer. The prepared samples were mounted on SEM stubs and observations were recorded. Confocal microscopic images of penetration of SiO2-NPs in the mycelia and conidia of P. vexans, SiO2-NPs attached with cells of R. solanacearum, and penetration of SiO2-NPs in M. incognita J2 were also taken.
2.4 In vitro study
In vitro studies of the effects of SiO2-NPs and TiO2-NPs on P. vexans fungus were investigated. Separately, 0.20 mg/mL of SiO2- and TiO2-NP suspensions were prepared, and 10 mL was added to 500 mL of properly sterilized potato dextrose agar (PDA) medium. Medium-containing Petri dishes inoculated with fungus P. vexans were kept for 2 weeks to screen the effect of both NPs on the fungal growth. To screen the effect of SiO2-NPs and TiO2-NPs on bacterium R. solanacearum, we used a paper disk of 7 mm diameter dipped it in 0.20 mg/mL of NP suspension, dried it for 30 min, and placed it on nutrient agar Petri plate inoculated with R. solanacearum. The antibacterial activity of both NPs was determined by the presence or absence of an inhibitory zone surrounding the Petri dish after 24 h of incubation. To examine the effect of SiO2 NPs/TiO2-NPs on the nematode M. incognita, 50 mL of distilled water was mixed with 0.20 mg/mL suspension (5 mL) and 50 mL of distilled water was placed in each petri-dish. For hatching, ten washed egg masses were placed in each Petri plate. The number of hatched juveniles from eggs was observed under the microscope.
2.5 Statistical analysis
Using the software R (3.6.1) of statistics, a two-way analysis of variance (package library, agricolae) was used to statistically evaluate the data. Duncan’s test was performed to evaluate whether the mean values were significantly different (p = 0.05).
2.6 Molecular docking
A silica NP model made up of (SiO2)72 cluster was used in the docking investigation. The NP framework was built directly using Cartesian atom coordinates derived from the literature [18]. PatchDock and FireDock software were used to conduct a molecular docking investigation [19,20]. Visualization of the best-docked pose was performed using the BIOVIA Discovery Studio Visualizer.
3 Results
3.1 Biological effects of SiO2-NPs and TiO2-NPs on bacteria, fungi, and nematodes
The inhibitory effect of SiO2-NPs was found higher on R. solanacearum than that of TiO2-NPs (Table 1; Figure 1c and g). An inhibition zone of 0.20 mg/mL of SiO2-NP and TiO2-NP was recorded at 0.62 and 0.51 mm, respectively, after 48 h of incubation (Table 1).
Impacts of SiO2-NPs and TiO2-NPs on fungus and bacteria in vitro, as well as effects of both NPs on M. incognita hatching and mortality
| Treatments | Inhibition zone (mm) | |
|---|---|---|
| SiO2 0.20 mg/mL | R. solanacearum | 0.62a |
| TiO2 0.20 mg/mL | R. solanacearum | 0.51b |
| Treatment | Antifungal activity (%) | |
|---|---|---|
| SiO2 0.20 mg/mL | P. vexans | 41.2a |
| TiO2 0.20 mg/mL | P. vexans | 32.9b |
| Treatments | After 48 h, J2 of M. incognita hatching | After 48 h, mortality of J2 |
|---|---|---|
| Distilled H2O | 476a | 3c |
| SiO2 0.20 mg/mL | 196c | 27a |
| TiO2 0.20 mg/mL | 313b | 15b |
At p ≤ 0.05, data analysis of significance was done by Duncan’s multiple range test. Within a column, the same letters are not significantly different.
(a and e) P. vexans growth on PDA medium. (b) P. vexans growth on PDA medium with 0.20 mg/mL suspension of SiO2-NPs. (f) P. vexans growth on PDA medium with 0.20 mg/mL solution of TiO2-NPs. (c) Inhibition zone present around a paper disk dipped in 0.20 mg/mL suspension of SiO2-NPs inoculated with R. solanacearum. (g) Inhibition zone formed around a paper disk dipped in 0.20 mg/mL suspension of TiO2-NPs. (d) Treated J2 of M. incognita with 0.20 mg/mL suspension of SiO2-NPs for 24 h. (h) Treated J2 of M. incognita with 0.20 mg/mL TiO2-NPs suspension for 24 h.
Both SiO2-NPs and TiO2-NPs showed antifungal activity against P. vexans (Table 1; Figure 1b and f). SiO2-NPs are more effective at inhibiting P. vexans than TiO2-NPs. A concentration of 0.20 mg/mL of SiO2-NPs resulted in a 41.2% reduction in the P. vexans growth, while 0.20 mg/mL of TiO2-NPs resulted in a 32.9% reduction in the fungal growth (Table 1).
A concentration of 0.20 mg/mL of both SiO2-NPs and TiO2-NPs was used to determine the influence on M. incognita mortality and hatching after 48 h of experiment setting (Table 1). SiO2-NPs reduce hatching higher than by TiO2-NPs. SiO2-NPs caused 58.82% inhibition in hatching over control while TiO2-NPs caused 34.24% inhibition in hatching. The mortality of the second-stage juveniles of M. incognita in SiO2-NPs was reported to be 81.0% while the mortality was 45.0% in TiO2-NPs after 48 h. It was observed that both NPs harm J2 of M. incognita (Figure 1d and h).
Scanning electron micrograph of P. vexans treated with SiO2-NPs and TiO2-NPs shows disturbed and fragmented mycelium and conidia (Figure 2). Deformed cells of R. solanacearum were also observed when treated with SiO2-NPs and TiO2-NPs. A disturbed cuticle layer of M. incognita’s second-stage juvenile was observed when added to the solution of SiO2-NPs and TiO2-NPs for hatching. Confocal microscopic images show the penetration of SiO2-NPs in mycelium and conidia of P. vexans (Figure 3). SiO2-NPs were also found attached to cells of R. solanacearum. Penetration of SiO2-NPs was also observed in the M. incognita (J2 juvenile) (Figure 3).
SEM images of test pathogens treated with SiO2-NPs and TiO2-NPs. (a and b) Mycelium and conidia of P. vexans sprayed with 0.20 mg/mL SiO2-NPs. (c) R. solanacearum handled with 0.20 mg/mL SiO2-NPs. (d) Nematode M. incognita handled with 0.20 mg/mL SiO2-NPs. (e and f) Mycelium and conidia of P. vexans handled with 0.20 mg/mL TiO2-NPs. (g) R. solanacearum treated with 0.20 mg/mL TiO2-NPs. (h) M. incognita J2 treated with 0.20 mg/mL TiO2-NPs.
Confocal microscopic images of test pathogens: (a and b) penetration of SiO2-NPs in the mycelia and conidia of P. vexans; (c) SiO2-NPs attached with cells of R. solanacearum; and (d) penetration of SiO2-NPs in M. incognita J2.
3.2 Impact of SiO2-NPs and TiO2-NPs on plants with single test pathogen
Plant fresh weight, plant length, shoot dry weight, root dry weight, leaf chlorophyll, and carotenoid were significantly affected by NPs and pathogens (p = 0.05).
3.2.1 Effect on the dry weight of shoot
Inoculation of test pathogens (i.e., P. vexans, R. solanacearum, and M. incognita) resulted in a considerable reduction in plant growth attributes. Inoculation of R. solanacearum caused the highest reduction in the plant growth followed by P. vexans and M. incognita (Table 2). A significant increase in plant growth attributes occurs after the foliar spray of TiO2/SiO2-NPs at all concentrations, i.e., 0.05, 0.10, and 0.20 mg/mL in comparison to the control one (Table 3). The highest increase in the plant growth was reported at 0.20 mg/mL SiO2-NPs followed by 0.10 mg/mL SiO2-NPs, 0.20 mg/mL TiO2, 0.05 mg/mL SiO2-NPs, and 0.10 mg/mL TiO2. Spray with 0.05 mg/mL TiO2-NPs was the least efficient for the management of pathogens (Table 2).
Effect of SiO2-NPs, TiO2 -NPs, P. vexans, M. incognita, including R. solanacearum on eggplant plant growth and photosynthetic pigments
| Treatment | Plant-length (cm) | Plant-fresh wt (g) | Shoot-dry wt (g) | Root-dry wt (g) | Chlorophyll in fresh leaves (mg/g) | Carotenoid in fresh leaves (mg/g) | Wilt/blight index |
|---|---|---|---|---|---|---|---|
| Control | 71.74a | 55.67a | 11.05a | 2.12a | 1.764a | 0.0595a | — |
| M. incognita | 62.30b | 47.92b | 10.35b | 1.78b | 1.500b | 0.0515b | — |
| P. vexans | 59.45c | 45.09c | 9.48c | 1.69c | 1.435c | 0.0490c | 2 |
| R. solanacearum | 57.52d | 42.35d | 8.48d | 1.51d | 1.355d | 0.0443d | 2 |
| Least mean square | 62.75 | 47.75 | 9.84 | 1.77 | 1.513 | 0.0510 | 2 |
| LSDP = 0.05 | 0.918 | 0.953 | 0.200 | 0.042 | 0.016 | 0.001 | |
| Control | 56.98g | 42.75f | 8.35g | 1.13g | 0.949g | 0.0432g | 3 |
| TiO2-0.05 mg/mL | 59.72f | 44.50e | 8.95f | 1.38f | 1.207f | 0.0465f | 2 |
| TiO2-0.10 mg/mL | 61.37e | 46.16d | 9.50e | 1.63e | 1.436e | 0.0501d | 2 |
| TiO2-0.20 mg/mL | 63.90c | 48.64c | 10.27c | 1.97c | 1.584c | 0.0528c | 2 |
| SiO2-0.05 mg/mL | 62.67d | 47.74c | 9.77d | 1.82d | 1.532d | 0.0498e | 2 |
| SiO2-0.10 mg/mL | 65.69b | 50.59b | 10.60b | 2.12b | 1.824b | 0.0557b | 2 |
| SiO2-0.20 mg/mL | 68.86a | 53.92a | 11.44a | 2.39a | 2.063a | 0.0592a | 1 |
| Least mean square | 62.74 | 47.75 | 9.84 | 1.77 | 1.513 | 0.0510 | 2 |
| LSDP = 0.05 | 1.214 | 1.261 | 0.265 | 0.056 | 0.021 | 0.001 | — |
Data analysis of significance was done with Duncan’s multiple range test at p ≤ 0.05. The same letters within a column are not significantly different.
Effect of SiO2-NPs and TiO2-NPs on the plant growth and photosynthetic pigments of eggplants inoculated with test pathogens, i.e., M. incognita, P. vexans, and R. solanacearum and uninoculated
| Treatment | Pathogens | Plant length (cm) | Plant fresh wt (g) | Shoot dry wt (g) | Root dry wt (g) | Chlorophyll in fresh leaves (mg/g) | Carotenoid in fresh leaves (mg/g) | Wilt/blight index |
|---|---|---|---|---|---|---|---|---|
| Control | CA | 67.72de | 52.17de | 9.71jk | 1.32o | 1.192l | 0.0508ijk | — |
| M | 56.93lmn | 42.88lmn | 8.65mnop | 1.20p | 1.058m | 0.0441qr | — | |
| P | 52.41op | 39.40op | 7.97q | 1.13p | 0.831o | 0.0433r | 3 | |
| R | 50.89q | 36.58q | 7.07r | 0.87q | 0.718p | 0.0349t | 3 | |
| TiO2-0.05 mg/mL | CB | 69.76cd | 53.22cde | 10.13ij | 1.61klm | 1.427j | 0.0527gh | — |
| M | 59.55jk | 44.81jkl | 9.33kl | 1.42o | 1.354k | 0.0479mn | — | |
| P | 55.63mno | 41.49mno | 8.56nop | 1.38o | 1.086m | 0.0461op | 2 | |
| R | 53.97op | 38.50pq | 7.81q | 1.11p | 0.964n | 0.0395s | 2 | |
| TiO2-0.10 mg/mL | CB | 71.55bc | 54.94cd | 11.04defg | 1.92ghi | 1.698g | 0.0576d | — |
| M | 61.11hij | 46.43ghijk | 9.89j | 1.63klm | 1.519i | 0.0504jkl | — | |
| P | 57.62klmn | 43.15lm | 8.98lmn | 1.54mn | 1.318k | 0.0492klm | 2 | |
| R | 55.21no | 40.15nop | 8.09pq | 1.44no | 1.211l | 0.0432r | 2 | |
| TiO2-0.20 mg/mL | CB | 72.12bc | 55.89bc | 11.49bcd | 2.28cd | 1.869d | 0.0598c | — |
| M | 64.51g | 48.52fgh | 10.63ghi | 1.96gh | 1.606h | 0.0538fg | — | |
| P | 60.75ij | 46.29ghijk | 10.23hij | 1.92ghi | 1.437j | 0.0518hij | 2 | |
| R | 58.22kl | 43.87klm | 8.73mno | 1.73jk | 1.424j | 0.0461op | 2 | |
| SiO2-0.05 mg/mL | CC | 70.94bc | 54.77cd | 10.89efg | 2.21de | 1.708fg | 0.0559e | — |
| M | 62.29ghi | 47.34ghij | 10.75fgh | 1.81ij | 1.517i | 0.0508ijk | — | |
| P | 59.63jk | 45.98hijk | 9.20klm | 1.69kl | 1.494i | 0.0473no | 2 | |
| R | 57.85klm | 42.87lmn | 8.27opq | 1.57lm | 1.412j | 0.0455pq | 2 | |
| SiO2-0.10 mg/mL | CC | 73.25b | 57.76b | 11.76bc | 2.59b | 2.067b | 0.0691b | — |
| M | 64.41g | 50.97ef | 11.32cdef | 2.11ef | 1.647h | 0.0549ef | — | |
| P | 63.22gh | 48.10ghi | 10.01j | 1.91ghi | 1.838de | 0.0502jkl | 2 | |
| R | 61.91hij | 45.55ijkl | 9.33kl | 1.88hi | 1.744f | 0.0488lmn | 2 | |
| SiO2-0.20 mg/mL | CC | 76.87a | 60.94a | 12.34a | 2.91a | 2.391a | 0.0707a | — |
| M | 67.31e | 54.54cd | 11.93ab | 2.35c | 1.803e | 0.0587cd | — | |
| P | 66.95ef | 51.23ef | 11.41bcde | 2.28cd | 2.047bc | 0.0555e | 1 | |
| R | 64.62fg | 48.97fg | 10.08ij | 2.02fg | 2.013c | 0.0521hi | 1 | |
| L.S.D. NPs × pathogens | 2.428 | 2.521 | 0.530 | 0.112 | 0.041 | 0.002 | ||
Data analysis was done by using Duncan’s multiple range test at p ≤ 0.05. The same letters within a column are not significantly different. M = M. incognita; P = P. vexans; R = R. solanacearum; AC = control without pathogen without SiO2-NPs and TiO2-NPs; BC = control without pathogen with TiO2-NPs; CC = control without pathogen with SiO2-NPs.
Spraying TiO2/SiO2-NPs at all concentrations on plants without pathogens resulted in a considerable increase in shoot dry weight compared to the uninoculated control (Table 3). The plants inoculated with P. vexans or M. incognita had similar shoot dry weight after spraying 0.20 mg/mL SiO2-NPs. The spraying of SiO2-NPs at 0.20 mg/mL to plants with M. incognita or P. vexans/R. solanacearum improves shoot dry weight more than caused by SiO2 0.10 mg/mL. The spraying of 0.10 mg/mL SiO2-NPs to plants with M. incognita/R. solanacearum improves shoot dry weight more than plants sprayed with 0.20 mg/mL TiO2 (Table 3).
Spraying 0.20 mg/mL TiO2-NPs to plants with M. incognita increased up to 22.89% shoot dry weight while a spray of plants with P. vexans and R. solanacearum caused 28.36 and 23.48% increases over their respective controls. Similarly, a foliar spray of 0.20 mg/mL SiO2-NPs to plants with M. incognita caused a 37.92% increase in shoot dry weight, while a spray of plants with P. vexans and R. solanacearum caused 43.16 and 42.57% increases over their respective controls (Table 3).
3.2.2 Effect on chlorophyll and carotenoid contents
A significant reduction in the chlorophyll and carotenoid content was found with R. solanacearum followed by P. vexans and M. incognita (Table 2). A significant increase in chlorophyll and carotenoid contents occurs after foliar spray at all concentrations of TiO2/SiO2-NPs in comparison to control (Table 2). The highest increase in total chlorophyll contents was reported at 0.20 mg/mL SiO2-NPs. Spraying with 0.05 mg/mL TiO2-NPs was found least effective in increasing chlorophyll and carotenoid contents (Table 2).
The spray of SiO2-NPs and TiO2-NPs at all three concentrations to uninoculated plants caused significant (p < 0.05) increases in chlorophyll and carotenoid contents over control (Table 3). Inoculation of either of the test pathogens caused a significant reduction in chlorophyll and carotenoid contents. The spray of SiO2-NPs at 0.20 mg/mL caused the highest increase in chlorophyll and carotenoid contents and the spray of 0.05 TiO2-NPs was found least effective. The chlorophyll content in plants with M. incognita increased 27.98 and 51.80% after the spray of 0.05 and 0.20 mg/mL TiO2-NPs, respectively, while plants with P. vexans and R. solanacearum caused a 72.92 and 98.32% increase over their respective controls after spraying 0.20 mg/mL TiO2-NPs. The spray of 0.05 TiO2-NPs to plants with P. vexans and R. solanacearum caused a 30.69 and 34.26% increase over their respective controls (Table 3). Similarly, the use of 0.20 and 0.05 mg/mL SiO2-NPs to plants with M. incognita caused a 70.42 and 43.38% increase in the chlorophyll content, respectively, while a spray of plants with P. vexans and R. solanacearum caused 79.78 and 96.65% increase over their respective controls after spraying with 0.05 TiO2-NPs. Foliar spray of 0.20 mg/mL SiO2-NPs to plants with P. vexans and R. solanacearum caused a 146.33 and 180.36% increase over their respective controls (Table 3).
Foliar spray of 0.20 mg/mL TiO2-NPs to plants with M. incognita caused a 21.99% increase in the carotenoid content while a spray of plants with P. vexans and R. solanacearum caused a 19.63 and 32.09% increase over their respective controls. Similarly, the use of 0.05 mg/mL SiO2-NPs to plants with M. incognita caused a 15.19% increase in the carotenoid content while a spray of plants with P. vexans and R. solanacearum caused a 9.23 and 30.37% increase over their respective controls. Spraying 0.20 mg/mL SiO2-NPs to plants with M. incognita caused a 33.11% increase in the carotenoid content while a spray of plants with P. vexans and R. solanacearum increased the carotenoid content by 28.18 and 49.28% over their respective controls (Table 3).
3.2.3 Effect on nematode population and galling
A significant population reduction and galling of M. incognita occur after foliar spray of TiO2/SiO2-NPs in all three concentrations (Figures 4 and 5). The significant (p < 0.05) highest reduction in nematode population and galling occur after the spray of plants with M. incognita at 0.20 mg/mL SiO2-NP treatment. R. solanacearum and P. vexans also harmed the galling and population of M. incognita (Figures 4 and 5).
Effect of SiO2-NPs and TiO2-NPs on root galling of M. incognita (M) inoculated alone (M) and in combination with P. vexans (P) and R. solanacearum (R). Error charts reflect the standard deviation.
Influence of SiO2-NPs and TiO2-NPs on the multiplication of M. incognita (M) inoculated alone (M) and in combination with P. vexans (P) and R. solanacearum (R). Error bars reflect the standard deviation.
3.2.4 Disease indices
Blight and wilt indices caused by P. vexans and R. solanacearum, respectively, were 3 (Table 2). Disease indices were reduced to 2 when TiO2-NPs at all concentrations and SiO2-NPs in two concentrations (0.05 mg or 0.10 mg/mL) were sprayed on plants with either of the test pathogens. Spraying with 0.20 mg/mL SiO2-NPs reduces disease indices to 1 when inoculated with either of the test pathogens (Table 3).
3.3 Effects of SiO2-NPs and TiO2-NPs on plants inoculated with two or three test pathogens
3.3.1 Effect on shoot dry weight
Inoculation of all three test pathogens together caused a significant (p < 0.05) reduction in shoot dry weight over the un-inoculated control (Table 4). Inoculation of all the three pathogens together caused the highest reduction in shoot dry weight followed by the inoculation of M. incognita plus R. solanacearum, M. incognita with P. vexans while R. solanacearum plus P. vexans caused the least reduction in shoot dry weight. Inoculation of SiO2-NPs or TiO2-NPs in all three concentrations caused a significant increase in shoot dry weight over the un-inoculated control. Application of 0.20 mg/mL SiO2-NPs has the potential to increase shoot dry weight followed by 0.10 mg/mL SiO2-NPs, 0.20 mg/mL TiO2-NPs, 0.05 mg/mL SiO2-NPs, and 0.10 mg/mL TiO2-NPs. Spraying with 0.05 mg/mL TiO2-NPs was found to be least effective. Inoculation of P. vexans plus M. incognita/M. incognita plus R. solanacearum/P. vexans plus R. solanacearum or all the three pathogens together caused a significant reduction in shoot dry weight (Table 5). The application of different concentrations of SiO2-NPs and TiO2-NPs resulted in a significant (p < 0.05) increase in shoot dry weight of pathogen-inoculated plants. Foliar spray of 0.20 mg/mL TiO2-NPs to plants with P. vexans plus M. incognita caused a 51.49% increase in shoot dry weight while M. incognita plus R. solanacearum, P. vexans plus R. solanacearum, and all the three pathogens together caused 63.62, 58.03, and 66.98% increases over their respective controls. Similarly, the use of 0.05 mg/mL SiO2-NPs to plants with P. vexans plus M. incognita caused a 49.34% increase in shoot dry weight while M. incognita plus R. solanacearum, P. vexans plus R. solanacearum, and all the three pathogens together caused 55.76, 54.29, and 67.46% increases over their respective controls. Foliar spray of 0.20 mg/mL SiO2-NPs to plants with P. vexans plus M. incognita caused a 78.64% increase in shoot dry weight while M. incognita plus R. solanacearum, P. vexans plus R. solanacearum, and all the three pathogens together caused 84.28, 77.54, and 123.99% increases over their respective controls (Table 5).
Effect of test pathogens inoculated in combination on the plant growth, chlorophyll, and carotenoid contents of eggplant
| Treatment | Plant-length (cm) | Plant-fresh weight (g) | Shoot-dry weight (g) | Root-dry weight (g) | Chlorophyll in fresh leaves (mg/g) | Carotenoid in fresh leaves (mg/g) | Wilt/blight index |
|---|---|---|---|---|---|---|---|
| Control | 71.74a | 55.67a | 11.05a | 2.12a | 1.764a | 0.0595a | — |
| M + P | 51.60c | 37.88c | 8.75c | 1.62c | 1.410c | 0.0418b | 3.14 |
| M + R | 47.38d | 37.67c | 8.32d | 1.46d | 1.328d | 0.0407c | 3.14 |
| R + P | 53.41b | 40.69b | 9.52b | 1.71b | 1.532b | 0.0436c | 3.14 |
| M + R + P | 40.56e | 28.73d | 6.96e | 1.36e | 1.090e | 0.0386d | 3.85 |
| Least mean square | 52.93 | 40.12 | 8.92 | 1.65 | 1.424 | 0.0440 | 3.31 |
| LSDP = 0.05 | 0.892 | 0.604 | 0.263 | 0.035 | 0.022 | 0.001 | |
| Control | 47.98f | 35.74g | 6.36g | 0.94g | 0.933g | 0.0322g | 5 |
| TiO2-0.05 mg/mL | 49.97e | 37.15f | 8.13f | 1.25f | 1.118f | 0.0349f | 4.25 |
| TiO2-0.10 mg/mL | 51.74d | 38.90e | 8.78e | 1.54e | 1.352e | 0.0443e | 3.25 |
| TiO2-0.20 mg/mL | 53.55c | 40.43d | 9.35c | 1.82c | 1.481c | 0.0479c | 3.25 |
| SiO2-0.05 mg/mL | 52.42d | 39.68c | 9.07d | 1.69d | 1.399d | 0.0456d | 3.25 |
| SiO2-0.10 mg/mL | 55.76b | 42.82b | 9.94b | 2.02b | 1.692b | 0.0506b | 2.25 |
| SiO2-0.20 mg/mL | 59.14a | 46.17a | 10.80a | 2.32a | 1.999a | 0.0527a | 2 |
| Least mean square | 52.93 | 40.12 | 8.92 | 1.65 | 1.424 | 0.0440 | 3.32 |
| LSDP = 0.05 | 1.05 | 0.715 | 0.311 | 0.042 | 0.026 | 0.001 |
Data analysis was done with Duncan’s multiple range test at p ≤ 0.05. Within a column, the same letters are not significantly different.
Effect of SiO2-NPs and TiO2-NPs on simultaneous inoculation of P. vexans, M. incognita, and R. solanacearum, as well as plant development, chlorophyll, and carotenoid content of eggplant
| Treatment | Pathogens | Plant-length (cm) | Plant-fresh wt (g) | Shoot-dry wt (g) | Root-dry wt (g) | Chlorophyll in fresh leaves (mg/g) | Carotenoid in fresh leaves (mg/g) | Wilt/Blight index |
|---|---|---|---|---|---|---|---|---|
| Control | CA | 67.72d | 52.17e | 9.71ghi | 1.32no | 1.192k | 0.0508de | — |
| M + P | 46.84klm | 34.11qr | 6.04rs | 0.82q | 0.893n | 0.0316pq | 5 | |
| M + R | 42.66no | 33.23r | 5.47s | 0.76q | 0.802o | 0.0302qr | 5 | |
| P + R | 49.13jk | 36.51nop | 6.41qr | 1.09p | 1.013m | 0.0331p | 5 | |
| M + R + P | 33.58q | 22.72u | 4.21t | 0.73q | 0.769o | 0.0290r | 5 | |
| TiO2-0.05 mg/mL | CB | 69.76cd | 53.22de | 10.13efg | 1.61jk | 1.427i | 0.0527d | — |
| M + P | 48.91jk | 35.92op | 7.83no | 1.28o | 1.023lm | 0.0401mn | 4 | |
| M + R | 44.89mn | 35.22pq | 7.65op | 1.05p | 1.018m | 0.0394n | 4 | |
| P + R | 50.91ij | 37.63lmno | 8.87jklm | 1.33no | 1.211k | 0.0359o | 4 | |
| M + R + P | 35.42q | 23.77u | 6.18rs | 1.02p | 0.912n | 0.0326pq | 5 | |
| TiO2-0.10 mg/mL | CB | 71.55bc | 54.94c | 11.04bcd | 1.92fgh | 1.698f | 0.0576bc | — |
| M + P | 50.75ij | 36.96no | 8.47klmn | 1.54kl | 1.339j | 0.0421jklm | 3 | |
| M + R | 46.14lm | 37.11no | 8.26lmno | 1.39mn | 1.238k | 0.0422jklm | 3 | |
| P + R | 52.15hi | 39.18jkl | 9.44ghij | 1.54kl | 1.475hi | 0.0409klmn | 3 | |
| M + R + P | 38.11p | 26.32t | 6.71qr | 1.35no | 1.014m | 0.0388n | 4 | |
| TiO2-0.20 mg/mL | CB | 72.12bc | 55.89c | 11.49bc | 2.28cd | 1.869d | 0.0598b | — |
| M + P | 52.62hi | 38.29jklmn | 9.15hijk | 1.83h | 1.503h | 0.0471fg | 3 | |
| M + R | 48.42jkl | 39.13jklm | 8.95ijkl | 1.55kl | 1.343j | 0.0453gh | 3 | |
| P + R | 54.41gh | 40.93hi | 10.13efg | 1.87gh | 1.611g | 0.0451ghi | 3 | |
| M + R + P | 40.22op | 27.94s | 7.03pq | 1.57kl | 1.079l | 0.0426ijklm | 4 | |
| SiO2-0.05 mg/mL | CC | 70.94bc | 54.77cd | 10.89cd | 2.21d | 1.708f | 0.0559c | — |
| M + P | 50.94ij | 37.55lmno | 9.02ijkl | 1.67ij | 1.436i | 0.0459g | 3 | |
| M + R | 47.04klm | 37.32mno | 8.52klmn | 1.47lm | 1.321j | 0.0432hijk | 3 | |
| P + R | 52.81hi | 40.03ij | 9.89fgh | 1.71i | 1.513h | 0.0428hijkl | 3 | |
| M + R + P | 40.37op | 28.73s | 7.05pq | 1.39mn | 1.017m | 0.0405lmn | 4 | |
| SiO2-0.10 mg/mL | CC | 73.25b | 57.76b | 11.76ab | 2.59b | 2.067b | 0.0691a | — |
| M + P | 53.73gh | 39.76ijk | 9.95fg | 1.98f | 1.691f | 0.0487ef | 2 | |
| M + R | 50.42ij | 39.12jklm | 9.33ghij | 1.95fg | 1.663fg | 0.0467fg | 2 | |
| P + R | 55.55fg | 43.78g | 10.55def | 2.08e | 1.806e | 0.0461g | 2 | |
| M + R + P | 45.87lm | 33.72qr | 8.14mno | 1.51kl | 1.235k | 0.0426ijklm | 3 | |
| SiO2-0.20 mg/mL | CC | 76.87a | 60.94a | 12.34a | 2.91a | 2.391a | 0.0707a | — |
| M + P | 57.41ef | 42.82g | 10.79cde | 2.23d | 1.987c | 0.0503de | 2 | |
| M + R | 52.12hi | 42.35gh | 10.08efg | 2.11e | 1.915d | 0.0488ef | 2 | |
| P + R | 58.93e | 46.78f | 11.38bc | 2.37c | 2.098b | 0.0491ef | 2 | |
| M + R + P | 50.38ij | 37.97klmn | 9.43ghij | 1.98f | 1.606g | 0.0447ghij | 2 | |
| L.S.D. p = 0.05 NPs × pathogens | 1.59 | 0.695 | 0.093 | 0.057 | 0.002 | 0.001 | ||
At p ≤ 0.05, data analysis was done with Duncan’s multiple range test. The same letters do not differ significantly within a column. M = M. incognita; P = P. vexans; R = R. solanacearum; AC = control without pathogen without SiO2-NPs and TiO2-NPs; BC = control without pathogen with TiO2-NPs; CC = control without pathogen with SiO2-NPs.
3.3.2 Effect on chlorophyll and carotenoid contents
Inoculation of test pathogens in combination resulted in a noteworthy reduction in contents of chlorophyll over the uninoculated control (Table 4). Inoculation of M. incognita plus P. vexans caused a 25.08% reduction in chlorophyll contents while a 32.72% reduction was caused by M. incognita plus R. solanacearum (% data not shown). Inoculation of P. vexans plus R. solanacearum and all the three pathogens together caused 15.02 and 35.49% reductions in chlorophyll contents, respectively. Foliar spray of 0.20 mg/mL TiO2-NPs to plants with M. incognita plus P. vexans caused a 68.31% increase in chlorophyll contents while M. incognita plus R. solanacearum, P. vexans plus R. solanacearum, and all the three pathogens together caused 67.46, 59.03, and 40.31% increases over their respective controls. Foliar spray of 0.20 mg/mL SiO2-NPs to plants with M. incognita plus P. vexans caused a 122.50% increase in chlorophyll contents while M. incognita plus R. solanacearum, P. vexans plus R. solanacearum, and all the three pathogens together caused 138.78, 107.11, and 108.84% increases over their respective controls (Table 5).
Inoculation of all the pathogens together caused a high reduction in carotenoid contents (Table 4). Inoculation of M. incognita plus P. vexans caused a 37.80% reduction in carotenoid contents while a 40.55% reduction was caused by M. incognita plus R. solanacearum (% data not shown). Inoculation of P. vexans plus R. solanacearum and all the three pathogens together caused 34.84 and 42.91% reductions in carotenoid, respectively. Spraying three pathogens together caused 50.0, 36.25, and 46.90% increases over their respective controls. Similarly, the use of 0.05 mg/mL SiO2-NPs to plants with M. incognita plus P. vexans caused a 54.11% increase in the carotenoid content while M. incognita plus R. solanacearum, P. vexans plus R. solanacearum, and all the three pathogens together caused 54.63, 39.27, and 46.90% increases over their respective controls. Spraying with 0.20 mg/mL SiO2-NPs to plants with M. incognita plus P. vexans caused a 59.18% increase in the carotenoid content while M. incognita plus R. solanacearum, P. vexans plus R. solanacearum, and all the three pathogens together caused 61.59, 48.34 and 54.14% increases over their respective controls (Table 5).
3.3.3 Blight and wilt indices
Blight and wilt indices were 5 when P. vexans, R. solanacearum, and M. incognita were inoculated in combinations (Table 5). Indices were recorded as 2 when plants inoculated with two or three pathogens were sprayed with 0.10 (mg/mL)/0.20 (mg/mL) SiO2-NPs except for plants inoculated with three pathogens sprayed with 0.10 mg/mL SiO2-NPs (Table 5).
3.3.4 Nematode multiplication and galling
Galling and multiplication of nematode significantly reduced after the application of SiO2-NPs followed by TiO2-NPs (Figures 4 and 5). The spray of 0.20 mg/mL SiO2-NPs resulted in the greatest reduction in galling and nematode population, whereas the spray of 0.05 TiO2-NPs resulted in the least. Inoculation of P. vexans or R. solanacearum also harmed galling and nematode multiplication. R. solanacearum showed a stronger detrimental effect on nematode multiplication and galling than P. vexans. Together had a greater adverse effect than alone (Figures 4 and 5).
3.4 Molecular docking analysis
R. solanacearum protein containing the X-ray crystallographic (PDB IDs: 1UQX and 3ZI8) was retrieved from the website of Protein Data Bank RCSB PDB. The bacterium R. solanacearum, which is found all over the world and causes deadly wilt in a wide range of crops, has been revealed to produce R. solanacearum lectin, a powerful l-fucose-binding lectin with a tandem repetition in its sequence of amino acids. The catastrophic bacterial wilt disease can be caused by a powerful l-fucose-binding lectin that can infect a wide spectrum of plants [21,22].
Docking was used to ascertain the best-docking pose of SiO2-NPs’ inactive pocket of amino acids of R. solanacearum of protein, as well as its binding affinity and confirmation within the binding sites. For the analysis and involvement of amino acids, the best-docking pose with a binding energy (global energy) of −31.61 and −43.00 kcal/mol was chosen for 1uqx.pdb and 3zi8.pdb, respectively. The important amino acids that participate in the nonbinding interaction with SiO2-NPs are LYS63, VAL5, GLN2, GLN3, ALA1, VAL76, LEU75, TYR101, ASP74, GLU94, SER73, PRO72, and LYS71 of the protein (1uqx.pdb) while amino acids, such as TYR37, THR38, GLU28, GLY39, ALA40, CYS30, TRP31, ASP32, LYS34, SER15, VAL13, TRP10, GLY11, TRP76, ASN79, GLY78, ILE59, LEU54, ALA58, SER57, and GLY56, for 3zi8.pdb found around the NPs stabilize the interaction between receptor and ligand (Figure 6).
Molecular docking study of NPs (c) against two receptors (a) PDB: 1uqx and (b) PDB: 3zib of R. solanacearum, (d and e) demonstrating active sites around NPs and (f and g) different non-bonding amino acid interactions with NPs.
4 Discussion
The growth of fungus P. vexans had been reduced when SiO2-NPs and TiO2-NPs were present in the PDA medium. In this study, SiO2-NPs were found more effective against P. vexans compared to TiO2-NPs. SEM photographs suggest that SiO2-NPs showed disturbed mycelia and conidia of P. vexans. Moreover, confocal images showed penetration of SiO2-NPs in mycelia and conidia. The antifungal property of silica NPs may be present due to the breakdown of the cell wall by forming hydrogen bonds between lipopolysaccharides present in the cell wall and hydroxyl groups present in silica NPs [23]. Silicon amendments have been shown to be effective at preventing fungal diseases [6,24]. SiO2-NPs were found effective against bacterial pathogens, such as Xanthomonas campestris pv. vesicatoria and R. solanacearum, and a few other tested pathogens in vitro and under greenhouse conditions [25].
The application of SiO2-NPs and TiO2-NPs exhibited antibacterial activity against R. solanacearum in the current study. Deformed cells of R. solanacearum were observed under the SEM when the bacterium was grown in the medium with the disk of SiO2-NPs. Foliar spray of SiO2-NPs was demonstrated to be superior to the TiO2-NPs foliar spray. Si mitigates disease intensity in crops [26]. Plants absorb Si in the mono-silicic acid form [27]. Si depositions in plant cell walls, leaves, and stems provide a barrier to host plants against pathogens. Lsi1 and Lsi2 are the transporters of Si present in the cell membrane of plants [28,29]. Polymerization of Si occurs in the extracellular spaces of epidermal cells and xylem vessels [30]. Ayana et al. [31] showed that the population of R. solanacearum was significantly reduced in Si fertilizer-treated tomato plants. Si could reduce bacterial diseases [32]. SEM micrograph showed deformed cells of R. solanacearum grown in the medium with the disk of TiO2-NPs. TiO2-NPs could inhibit the development of bacterial pathogens. TiO2-NPs at 200 mg/L inhibit the progress of fungus Rhizoctonia solani, bacterium Pectobacterium betavasculorum, and hatching of root-knot nematode (M. incognita) [33]. Norman and Chen [34] found that TiO2-NPs’ treatment reduces 93% of lesions caused by X. axonopodis pv. poinsettiicola in poinsettia plants treated with 75 mm. The TiO2-NPs’ treatment could modify the bacterial community structure [35]. Therefore, the current study confirmed that the application of foliar of SiO2-NPs and TiO2-NPs is effective in reducing the disease complex of eggplant.
The adverse effect of SiO2-NPs and TiO2-NPs was also observed on eggs and J2 was referred to the second-stage juveniles of M. incognita. Sudanophilic lipids and weakly acidic mucopolysaccharides are present in nematode cuticles. In addition, nematodes’ hypodermis contains lipids, glycogen, and acidic muco-polysaccharides [36]. The SEM of second-stage juveniles of M. incognita confirmed that the application of SiO2-NPs/TiO2-NPs harmed nematodes cuticle by affecting glycogen, lipid, and mucopolysaccharides. These are also found to have the potential to reduce galling and multiplication of M. incognita on eggplant. Si application dramatically reduced root-knot nematodes in the roots of the hosts and Si-treated plants have high phenolic compounds and high callose deposition in roots after nematode attack [37]. Similarly, M. incognita J2 mortality was 4.3 and 2% was observed in 800 and 400 mg/mL of TiO2-NPs [38].
Previous studies reported that 500 mg/L SiNPs and SiO2-NPs’ treatment increased plant growth and improved seed germination in maize crops [39,40]. Improvement in the seed germination of soybean was reported after treatment with nano-SiO2 and nano-TiO2 and they also improve the water- and nutrient-absorbing ability of seeds [8,41].
Plants sprayed with TiO2-NPs have increased photosynthesis plant growth and chlorophyll contents [42]. Applications of TiO2-NPs (<20 nm in size) increased shoot lengths, root length, chlorophyll content, and phosphorus uptake in wheat [43]. An increase in the growth of eggplants without pathogens by the application of SiO2-NPs and TiO2-NPs may be attributed to the above-mentioned reasons. Kang et al. [44] reported that silica NPs reduce the growth of Fusarium fungus and improve the growth of the Watermelon (Citrullus lanatus) plant. Ahamad and Siddiqui [45] found SiO2-NPs to be most effective against M. incognita compared to ZnO and TiO2-NPs. Spraying carrot plants with SiO2-NPs had the greatest impact on plant growth parameters. The docking study of NPs showed better activity against R. solanacearum carried out to understand the involvement of various amino acids with hydrophobic and hydrophilic nature residues of the protein. Certain amino acids (Figure 6) in 1uqx.pdb, such as ALA1, GLN2, LYS63, ASP74, LEU75, VAL76, and ASP74, as well as some amino acids in 3zi8.pdb, such as TRP10, SER15, TYR37, SER57, ALA58, ASN79, and TYR37, form hydrogen bonds with oxygen atoms of SiO2-NPs, and other nonbonding interactions can hinder microbe proliferation in the host plant. The nature of the contact, as well as active residues that are critical to the growth of R. solanacearum in various plants, is disclosed by molecular docking. To develop antimicrobial drugs in the future, a mechanistic method based on molecular docking could be interpreted by taking into account the amino acid residues of bacterial and fungal proteins.
5 Conclusion
Wilt and blight indices were reduced by the application of SiO2/TiO2-NPs. The reduction in disease indices by SiO2/TiO2-NPs also confirms the antibacterial and antifungal efficiencies of used NPs. The application of SiO2-NPs will be eco-friendly and can be used as an alternative to chemical pesticides to manage the disease complex of eggplant. A molecular docking investigation was also conducted to learn more about the interaction of SiO2-NPs with the protein of R. solanacearum at the binding site. Certain amino acid residues of bacterium explained in the discussion part formed hydrogen bonds with SiO2-NPs’ surface.
-
Funding information: This study was funded by the Researchers Supporting Project Number (RSP-2021/339), King Saud University, Riyadh, Saudi Arabia.
-
Author contributions: All authors have accepted responsibility for the entire content of this article and approved its submission.
-
Conflict of interest: The authors state no conflict of interest.
References
[1] FAO, World Health Organization; WHO Expert Committee on Food Additives. evaluation of certain contaminants in food: eighty-third report of the joint FAO/WHO expert committee on food additives; 2017. Geneva, Switzerland: World Health Organization.Search in Google Scholar
[2] Abad P, Gouzy J, Aury JM, Castagnone-Sereno P, Danchin EG, Deleury E, et al. Genome sequence of the metazoan plant-parasitic nematode Meloidogyne incognita. Nat Biotech. 2008;8:909–15.10.1038/nbt.1482Search in Google Scholar
[3] Mathew R, Opperman CH. The genome of the migratory nematode, Radopholus similis, reveals signatures of close association to the sedentary cyst nematodes. PLoS One. 2019;14(10):e0224391.10.1371/journal.pone.0224391Search in Google Scholar
[4] Khan M, Khan AU, Hasan MA, Yadav KK. Agro-nanotechnology as an emerging field: a novel sustainable approach for improving plant growth by reducing biotic stress. Appl Sci. 2021;11:2282.10.3390/app11052282Search in Google Scholar
[5] Rana RA, Siddiqui M, Skalicky M, Brestic M, Hossain A, Kayesh E, et al. Prospects of nanotechnology in improving the productivity and quality of horticultural crops. Horticulturae. 2021;7(10):332.10.3390/horticulturae7100332Search in Google Scholar
[6] Derbalah A, Shenashen M, Hamza A, Mohamed A, El Safty S. Antifungal activity of fabricated mesoporous silica nanoparticles against early blight of tomato. Egypt J Basic Appl Sci. 2018;5:145–50.10.1016/j.ejbas.2018.05.002Search in Google Scholar
[7] Norman S, Hongda C. IB in depth. special section on nanobiotechnology, Part 2. Ind Biotechnol. 2013;9:17–8.Search in Google Scholar
[8] Zheng L, Hong F, Lu S, Liu C. Effect of nano-TiO2 on strength of naturally aged seeds and growth of spinach. Biol Trace Elem Res. 2005;104:83–91.10.1385/BTER:104:1:083Search in Google Scholar
[9] Alghuthaymi MA, Almoammar H, Rai M, Said-Galiev E, Abd-Elsalam KA. Myconanoparticles: synthesis and their role in phytopathogens management. Biotechnol Biotechnol Equip. 2015;29(2):221–36.10.1080/13102818.2015.1008194Search in Google Scholar PubMed PubMed Central
[10] Yadav T, Mungray AA, Mungray AK. Fabricated nanoparticles. Rev Env Contam Toxicol. 2014;230:83–110.10.1007/978-3-319-04411-8_4Search in Google Scholar
[11] Bao-shan L, Chun-hui L, Li-jun F, Shu-chun Q, Min Y. Effect of TMS (nanostructured silicon dioxide) on growth of Changbai larch seedlings. J Res. 2004;15:138–40.10.1007/BF02856749Search in Google Scholar
[12] Rajput VD, Minkina T, Feizi M, Kumari A, Khan M, Mandzhieva S, et al. Effects of silicon and silicon-based nanoparticles on rhizosphere microbiome, plant stress and growth. Biology. 2021;10(8):791.10.3390/biology10080791Search in Google Scholar PubMed PubMed Central
[13] Wang M, Gao L, Dong S, Sun Y, Shen Q, Guo S. Role of silicon on plant–pathogen interactions. Front Plant Sci. 2017;8:701.10.3389/fpls.2017.00701Search in Google Scholar PubMed PubMed Central
[14] Nair R, Varghese SH, Nair BG, Maekawa T, Yoshida Y, Kumar DS. Nanoparticulate material delivery to plants. Plant Sci. 2010;179:154–63.10.1016/j.plantsci.2010.04.012Search in Google Scholar
[15] Gohari G, Mohammadi A, Akbari A, Panahirad S, Dadpour MR, Fotopoulos V, et al. Titanium dioxide nanoparticles (TiO2 NPs) promote growth and ameliorate salinity stress effects on essential oil profile and biochemical attributes of Dracocephalummoldavica. Sci Rep. 2020;10(1):1–14.10.1038/s41598-020-57794-1Search in Google Scholar PubMed PubMed Central
[16] Siddiqui ZA, Khan MR, Abd_Allah EF, Parveen A. Titanium dioxide and zinc oxide nanoparticles affect some bacterial diseases, and growth and physiological changes of beetroot. Int J Veg Sci. 2019;25(5):409–30.10.1080/19315260.2018.1523267Search in Google Scholar
[17] Khan M, Siddiqui ZA. Interaction of Meloidogyne incognita, Ralstonia solanacearum and Phomopsis vexans on eggplant in the sand mix and fly ash mix soils. Sci Horticulturae. 2017;225:177–84.10.1016/j.scienta.2017.06.016Search in Google Scholar
[18] Capeletti LB, de Oliveira LF, Goncalves KDA, de Oliveira JFA, Saito A, Kobarg J, et al. Tailored silica–antibiotic nanoparticles: overcoming bacterial resistance with low cytotoxicity. Langmuir. 2014;30:7456–64.10.1021/la4046435Search in Google Scholar PubMed
[19] Munde MS, Gao DZ, Shluger AL. Diffusion and aggregation of oxygen vacancies in amorphous silica. J Phys Condens Matter. 2017;29:245701.10.1088/1361-648X/aa6f9aSearch in Google Scholar PubMed
[20] Schneidman-Duhovny D, Inbar Y, Nussinov R, Wolfson HJ. PatchDock and SymmDock: servers for rigid and symmetric docking. Nucl Acids Res. 2005;33:W363–7.10.1093/nar/gki481Search in Google Scholar PubMed PubMed Central
[21] Andrusier N, Nussinov R, Wolfson HJ. FireDock: fast interaction refinement in molecular docking. Proteins. 2007;69:139–59.10.1002/prot.21495Search in Google Scholar PubMed
[22] Kostlánová N, Mitchell EP, Lortat-Jacob H, Oscarson S, Lahmann M, Gilboa-Garber N, et al. The fucose-binding lectin from Ralstonia solanacearum. A new type of beta-propeller architecture formed by oligomerization and interacting with fucoside, fucosyllactose, and plant xyloglucan. J Biol Chem. 2005;280:27839–49.10.1074/jbc.M505184200Search in Google Scholar PubMed
[23] Zuluaga AP, Puigvert M, Valls M. Novel plant inputs influencing Ralstonia solanacearum during infection. Front Microbiol. 2013;4:349.10.3389/fmicb.2013.00349Search in Google Scholar PubMed PubMed Central
[24] Bélanger RR, Benhamou N, Menzies JG. Cytological evidence of an active role of silicon in wheat resistance to powdery mildew (Blumeria graminis f. sp. tritici). Phytopathology. 2003;93:402–12.10.1094/PHYTO.2003.93.4.402Search in Google Scholar
[25] Parveen A, Siddiqui ZA. Impact of silicon dioxide nanoparticles on growth, photosynthetic pigments, proline, activities of defense enzymes and some bacterial and fungal pathogens of tomato. Vegetos. 2022;35:83–93.10.1007/s42535-021-00280-4Search in Google Scholar
[26] Pozza EA, Pozza AAA, Botelho DMDS. Silicon in plant disease control. Rev Ceres. 2015;62:323–31.10.1590/0034-737X201562030013Search in Google Scholar
[27] Rao GB, Susmitha P. Silicon uptake, transportation and accumulation in Rice. J Pharmacogn Phytochem. 2017;6(6):290–3.Search in Google Scholar
[28] Ma JF, Yamaji N. Silicon uptake and accumulation in higher plants. Trends Plant Sci. 2006;11(8):392–7.10.1016/j.tplants.2006.06.007Search in Google Scholar
[29] Ma JF, Yamaji N. Functions and transport of silicon in plants. Cell Mol Life Sci. 2008;65:3049–57.10.1007/s00018-008-7580-xSearch in Google Scholar
[30] Fawe A, Menzies JG, Chérif M, Bélanger RR. Silicon and disease resistance in dicotyledons. Stud Plant Sci. 2001;8:159–69.10.1016/S0928-3420(01)80013-6Search in Google Scholar
[31] Ayana G, Fininsa C, Ahmed S, Wydra K. Effects of soil amendment on bacterial wilt caused by Ralstoniasolanacerum and tomato yields in Ethiopia. J Plant Prot Res. 2011;51:673–81.10.2478/v10045-011-0013-0Search in Google Scholar
[32] Sakr N. The role of silicon (Si) in increasing plant resistance against fungal diseases. Hell Plant Prot J. 2016;9:1–15.10.1515/hppj-2016-0001Search in Google Scholar
[33] Khan MR, Siddiqui ZA. Efficacy of titanium dioxide nanoparticles in the management of disease complex of beetroot (Beta vulgaris L.) caused by Pectobacterium betavasculorum, Rhizoctonia solani, and Meloidogyne incognita. Gesunde Pflanz. 2021;73:445–64.10.1007/s10343-021-00566-2Search in Google Scholar
[34] Norman DJ, Chen J. Effect of foliar application of titanium dioxide on bacterial blight of geranium and xanthomonas leaf spot of poinsettia. Hort Sci. 2011;46:426–8.10.21273/HORTSCI.46.3.426Search in Google Scholar
[35] Simonin M, Richaume A, Guyonnet JP, Dubost A, Martins JM, Pommier T. Titanium dioxide nanoparticles strongly impact soil microbial function by affecting archaeal nitrifiers. Sci Rep. 2016;6:33643.10.1038/srep33643Search in Google Scholar
[36] Sood ML, Kalra S. Histochemical studies on the body wall of nematodes: Haemonchuscontortus (Rud., 1803) and Xiphinemainsigne Loos, 1949. Z für Parasitenkunde. 1977;51:265–73.10.1007/BF00384813Search in Google Scholar
[37] Zhan LP, Peng DL, Wang XL, Kong LA, Peng H, Liu SM, et al. Priming effect of root-applied silicon on the enhancement of induced resistance to the root-knot nematode Meloidogyne graminicola in rice. BMC Plant Biol. 2018;18:50–7.10.1186/s12870-018-1266-9Search in Google Scholar
[38] Ardakani AS. Toxicity of silver, titanium and silicon nanoparticles on the root knot nematode Meloidogyne incognita and growth parameter of tomato. Nematology. 2013;15:671–7.10.1163/15685411-00002710Search in Google Scholar
[39] Suriyaprabha R, Karunakaran G, Yuvakkumar R, Rajendran V, Kannan N. Silica nanoparticles for increased silica availability in maize (Zea mays. L) seeds under hydroponic conditions. Curr Nanosci. 2012;8:902–8.10.2174/157341312803989033Search in Google Scholar
[40] Hafez EM, Osman HS, Gowayed SM, Okasha SA, Omara AED, Sami R, et al. Minimizing the adversely impacts of water deficit and soil salinity on maize growth and productivity in response to the application of plant growth-promoting rhizobacteria and silica nanoparticles. Agronomy. 2021;11(4):676.10.3390/agronomy11040676Search in Google Scholar
[41] Lu CM, Zhang CY, Wen JQ, Wu GR, Tao MX. Research on the effect of nanometer materials on germination and growth enhancement of Glycine max and its mechanism. Soybean Sci. 2002;21:68–172.Search in Google Scholar
[42] Hong F, Zhou J, Liu C, Yang F, Wu C, Zheng L, et al. Effect of nano-TiO2 on photochemical reaction of chloroplasts of spinach. Biol Trace Elem Res. 2005;105:269–79.10.1385/BTER:105:1-3:269Search in Google Scholar
[43] Rafique R, Zahra Z, Virk N, Shahid M, Pinelli E, Park TJ, et al. Dose-dependent physiological responses of Triticum aestivum L. to soil applied TiO2 nanoparticles: Alterations in chlorophyll content, H2O2 production, and genotoxicity. Agric Ecosyst Env. 2018;255:95–101.10.1016/j.agee.2017.12.010Search in Google Scholar
[44] Kang H, Elmer W, Shen Y, Zuverza‐Mena N, Ma C, Botella P, et al. Silica nanoparticle dissolution rate controls the suppression of fusarium wilt of watermelon (Citrullus lanatus). Env Sci Technol. 2021;55(20):13513–22.10.1021/acs.est.0c07126Search in Google Scholar PubMed
[45] Ahamad L, Siddiqui ZA. Effects of silicon dioxide, zinc oxide and titanium dioxide nanoparticles on Meloidogyne incognita, Alternaria dauci and Rhizoctonia solani disease complex of carrot. Exp Parasit. 2021;230:108176.10.1016/j.exppara.2021.108176Search in Google Scholar PubMed
© 2022 Masudulla Khan et al., published by De Gruyter
This work is licensed under the Creative Commons Attribution 4.0 International License.
