Current techniques for plant virus detection, such as RT- PCR and ELISA, require multistep procedures and rely on sophisticated equipment. Due to the global spread of plant viruses, the development of simpler, faster and cheaper assay methods is inevitable. Gold nanoparticles -AuNPs- had raised much interest during recent years due to their novel optical properties or diagnostic purposes. The localized surface plasmon resonance -LSPR1- of AuNPs had been used in the development of novel colorimetric nano-biosensing systems. The frequency and intensity of the LSPR peak generally depend on the shape, size and the surrounding medium of the AuNPs. In this study, unmodified AuNPs had been used to detect the unamplified Tomato yellow leaf curl virus -TYLCV- genome in infected plants. A specific DNA probe complementary to the coat protein region of virus genome was designed. The extracted total DNA of uninfected and infected plants was mixed with hybridization buffer and the designed probe. The mixture was denatured, annealed and then cooled to room temperature and was followed by AuNPs addition. The color changes in the samples indicating the presence of target virus infections were ssessed visually after the addition of salt and confirmed by UV–Vis spectroscopy. The results showed that this trategy allowed for fast and sensitive detection of TYLCV genome and eliminated the need for PCR amplification and detection equipment.

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