Mishra Sandhya, Singh Braj Raj, Singh Akanksha, Keswani Chetan, Naqvi Alim H, Singh H B
Department of Mycology and Plant Pathology, Institute of Agricultural Sciences, Banaras Hindu University, Varanasi, India.
Centre of Excellence in Materials Science (Nanomaterials), Department of Applied Physics, Z. H. College of Engineering and Technology, Aligarh Muslim University, Aligarh, India.
PLoS One. 2014 May 19;9(5):e97881. doi: 10.1371/journal.pone.0097881. eCollection 2014.
The present study is focused on the extracellular synthesis of silver nanoparticles (AgNPs) using culture supernatant of an agriculturally important bacterium, Serratia sp. BHU-S4 and demonstrates its effective application for the management of spot blotch disease in wheat. The biosynthesis of AgNPs by Serratia sp. BHU-S4 (denoted as bsAgNPs) was monitored by UV-visible spectrum that showed the surface plasmon resonance (SPR) peak at 410 nm, an important characteristic of AgNPs. Furthermore, the structural, morphological, elemental, functional and thermal characterization of bsAgNPs was carried out using the X-ray diffraction (XRD), electron and atomic microscopies, energy dispersive X-ray (EDAX) spectrometer, FTIR spectroscopy and thermogravimetric analyzer (TGA), respectively. The bsAgNPs were spherical in shape with size range of ∼10 to 20 nm. The XRD and EDAX analysis confirmed successful biosynthesis and crystalline nature of AgNPs. The bsAgNPs exhibited strong antifungal activity against Bipolaris sorokiniana, the spot blotch pathogen of wheat. Interestingly, 2, 4 and 10 µg/ml concentrations of bsAgNPs accounted for complete inhibition of conidial germination, whereas in the absence of bsAgNPs, conidial germination was 100%. A detached leaf bioassay revealed prominent conidial germination on wheat leaves infected with B. sorokiniana conidial suspension alone, while the germination of conidia was totally inhibited when the leaves were treated with bsAgNPs. The results were further authenticated under green house conditions, where application of bsAgNPs significantly reduced B. sorokiniana infection in wheat plants. Histochemical staining revealed a significant role of bsAgNPs treatment in inducing lignin deposition in vascular bundles. In summary, our findings represent the efficient application of bsAgNPs in plant disease management, indicating the exciting possibilities of nanofungicide employing agriculturally important bacteria.
本研究聚焦于利用农业重要细菌粘质沙雷氏菌BHU-S4的培养上清液进行细胞外合成银纳米颗粒（AgNPs），并展示了其在小麦叶枯病防治中的有效应用。通过紫外可见光谱监测粘质沙雷氏菌BHU-S4合成AgNPs（标记为bsAgNPs）的过程，该光谱显示在410nm处有表面等离子体共振（SPR）峰，这是AgNPs的一个重要特征。此外，分别使用X射线衍射（XRD）、电子显微镜和原子显微镜、能量色散X射线（EDAX）光谱仪、傅里叶变换红外光谱（FTIR）和热重分析仪（TGA）对bsAgNPs进行了结构、形态、元素、功能和热性质表征。bsAgNPs呈球形，尺寸范围约为10至20nm。XRD和EDAX分析证实了AgNPs的成功生物合成及其晶体性质。bsAgNPs对小麦叶枯病病原菌小麦根腐离蠕孢表现出强烈的抗真菌活性。有趣的是，2、4和10μg/ml浓度的bsAgNPs可完全抑制分生孢子萌发，而在没有bsAgNPs的情况下，分生孢子萌发率为100%。离体叶片生物测定表明，单独感染小麦根腐离蠕孢分生孢子悬浮液的小麦叶片上分生孢子大量萌发，而用bsAgNPs处理叶片后，分生孢子萌发完全受到抑制。在温室条件下进一步验证了该结果，在温室中施用bsAgNPs可显著减少小麦植株中小麦根腐离蠕孢的感染。组织化学染色显示，bsAgNPs处理在诱导维管束中木质素沉积方面发挥了重要作用。总之，我们的研究结果表明bsAgNPs在植物病害管理中的有效应用，显示了利用农业重要细菌开发纳米杀菌剂的令人兴奋的可能性。
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