Tobacco mosaic virus (TMV) is a major pathogen affecting tomato plants worldwide. The efficacy of silver nanoparticles (Ag-NPs) mediated by Punica granatum biowaste peel extract in mitigating the negative impact of TMV infection on tomato growth and oxidative stress was investigated through scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-Visible (UV-Vis) spectrophotometer, X-ray Diffraction (XRD), dynamic light scattering (DLS), zeta potential, energy-dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared spectra (FTIR). Results of SEM analysis of green Ag-NPs revealed the presence of condensed spherical or round NPs with diameters ranging between 61 and 97 nm. TEM confirmed the SEM results and showed round-shaped Ag-NPs with an average size of 33.37 ± 12.7 nm. The elemental analysis (EDX) of prepared Ag-NPs revealed the presence of elemental Ag as a major peak (64.43%) at 3–3.5 KeV. The FTIR revealed several functional groups on the prepared Ag-NPs, for which three treatment strategies for Ag-NP applications were evaluated in the greenhouse study and compared to inoculated TMV and control plants: pre-infection treatment (TB), post-infection treatment (TA), and dual treatment (TD). The results showed that the TD strategy is the most effective in improving tomato growth and reducing viral replication, whereas all Ag-NP treatments (TB, TA, and TD) were found to significantly increase expression of the pathogenesis-related (PR) genes PR-1 and PR-2, as well as polyphenolic compounds, HQT, and C4H genes compared to control plants. In contrast, the flavonoid content of tomato plants was not affected by the viral infection, while the phenolic content was significantly reduced in the TMV group. Furthermore, TMV infection led to a significant increase in oxidative stress markers MDA and H2O2, as well as a reduction in the enzymatic activity of the antioxidants PPO, SOD, and POX. Our results clearly showed that the application of Ag-NPs on TMV-infected plants reduces virus accumulation, delays viral replication in all treatments, and greatly enhances the expression of the CHS gene involved in flavonoid biosynthesis. Overall, these findings suggest that treatment with Ag-NPs may be an effective strategy to mitigate the negative impact of TMV infection on tomato plants.
In this study, we used RT-qPCR to examine how PR genes were expressed in model tomato (Solanum lycopersicum L.) plants that had been infected with TMV or CMV. Under greenhouse conditions, the indirect ELISA data showed that both viruses were detected for the first time at 6 dpi. Then, the levels of accumulation increased very quickly, reaching a peak of 15 dpi. During the course of the study (1–15 dpi), the Delta CT, NormFinder, BestKeeper, and GeNorm software tools revealed that the β-actin gene was the most informative reference gene in the virally infected tomato tissues. For both the TMV- and CMV-infected tomato plants, the transcriptional expression levels of most tested genes changed between activation and repression, especially in the first 12 dpi. Compared to mock-inoculated plants, the expression levels of PR-1 were induced at all time intervals except at 8 dpi for CMV and at 6, 7, and 8 dpi for TMV infection. Conversely, the greater activation and accumulation of both viruses were associated with the greater up-regulation of PR-2 at 8 dpi, with relative expression levels of 7.28- and 5.84-fold for TMV and CMV, respectively. The up-regulated expression of PR-3, PR-4, and PR-7 was shown at 4 dpi. In contrast, the PR-5 gene was inhibited in TMV at 1 dpi until 9 dpi, and the induction of this gene at 10 dpi increased by 1.72-fold, but PR-5 was observed to up-regulate the expression of CMV at 1 dpi. This study provides the first valuable information on the comparative transcriptional levels of these tomato genes between TMV and CMV infections.
Plant diseases significantly reduce crop yields, threatening food security and agricultural sustainability. Fungi are the most destructive type of phytopathogen, and they are responsible for major yield losses in some of the most crucial crops grown across the world. In this study, a fungus isolate was detected from infected tomato plants and molecularly identified as Pythium aphanidermatum (GenBank accession number MW725032). This fungus caused damping-off disease and was shown to be pathogenic. Moreover, the expression of five pathogenesis-related genes, namely PR-1, PR-2, PR-3, PR-4, and PR-5, was quantitatively evaluated under the inoculation of tomato with P. aphanidermatum. The quantitative polymerase chain reaction (qPCR) showed that the expression levels of PR-1, PR-2, and PR-5 genes went up significantly at 5 days post-inoculation (dpi). The expression of the PR-1 gene also increased the variably, which reached its highest value at 20 dpi, with a reported relative expression level 6.34-fold higher than that of the control. At 15 dpi, PR-2 and PR-5 increased the most, while PR-1, PR-3, and PR-5 also increased noticeably at 20 dpi. On the contrary, PR-4 gene expression significantly decreased after inoculation, at all time intervals. Regarding PR-5 gene expression, the data showed a variable change in PR-5 gene expression at a different sample collection period. Still, it was highly expressed at 15 dpi and reached 3.99-fold, followed by 20 dpi, where the increasing percentage reached 3.70-fold, relative to the untreated control. The HPLC analysis indicated that the total concentration of all detected polyphenolic compounds was 3858 µg/g and 3202.2 µg/g in control and infected plant leaves, respectively. Moreover, the HPLC results concluded that Pythium infection decreased phenolic acids, such as chlorogenic and ellagic acids, which correlated with the infection–plant complex process. Based on the results, P. aphanidermatum could be a biotic stress pathogen that causes the expression of pathogen-related genes and stops the regulation of defensin phenolic compounds.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.