Al-Askar Abdulaziz A, Aseel Dalia G, El-Gendi Hamada, Sobhy Sherien, Samy Marwa A, Hamdy Esraa, El-Messeiry Sarah, Behiry Said I, Elbeaino Toufic, Abdelkhalek Ahmed
Department of Botany and Microbiology, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451, Saudi Arabia.
Plant Protection and Biomolecular Diagnosis Department, Arid Lands Cultivation Research Institute, City of Scientific Research and Technological Applications, Alexandria 21934, Egypt.
Plants (Basel). 2023 May 25;12(11):2103. doi: 10.3390/plants12112103.
Tobacco mosaic virus (TMV) is a major pathogen affecting tomato plants worldwide. The efficacy of silver nanoparticles (Ag-NPs) mediated by 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 HO, 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.
烟草花叶病毒（TMV）是一种影响全球番茄植株的主要病原体。通过扫描电子显微镜（SEM）、透射电子显微镜（TEM）、紫外可见（UV-Vis）分光光度计、X射线衍射（XRD）、动态光散射（DLS）、zeta电位、能量色散X射线光谱（EDX）和傅里叶变换红外光谱（FTIR），研究了生物废弃物果皮提取物介导的银纳米颗粒（Ag-NPs）在减轻TMV感染对番茄生长和氧化应激的负面影响方面的功效。绿色Ag-NPs的SEM分析结果显示存在直径在61至97纳米之间的凝聚球形或圆形纳米颗粒。TEM证实了SEM结果，并显示平均尺寸为33.37±12.7纳米的圆形Ag-NPs。制备的Ag-NPs的元素分析（EDX）显示在3-3.5 keV处存在元素Ag作为主要峰（64.43%）。FTIR揭示了制备的Ag-NPs上的几个官能团，在温室研究中评估了Ag-NP应用的三种处理策略，并与接种TMV的植物和对照植物进行了比较：感染前处理（TB）、感染后处理（TA）和双重处理（TD）。结果表明，TD策略在改善番茄生长和减少病毒复制方面最有效，而与对照植物相比，所有Ag-NP处理（TB、TA和TD）均显著增加了病程相关（PR）基因PR-1和PR-2以及多酚化合物、HQT和C4H基因的表达。相比之下，番茄植株的类黄酮含量不受病毒感染的影响，而TMV组中的酚类含量显著降低。此外，TMV感染导致氧化应激标志物MDA和HO显著增加，以及抗氧化剂PPO、SOD和POX的酶活性降低。我们的结果清楚地表明，在TMV感染的植物上施用Ag-NPs可减少病毒积累，在所有处理中延迟病毒复制，并极大地增强参与类黄酮生物合成的CHS基因的表达。总体而言，这些发现表明用Ag-NPs处理可能是减轻TMV感染对番茄植株负面影响的有效策略。
