Development of a quantum dots FRET-based biosensor for efficient detection of Polymyxa betae

Rhizomania is the most destructive disease in sugar beet throughout the world. The disease is caused by Beet necrotic yellow vein virus (BNYVV). Polymyxa betae (Keskin) is the only known vector of BNYVV, for transmission of the virus between the plants. Developing molecular diagnostic methods has a major impact on forecasting and epidemiological studies as well as screening sugar beet plants used in resistance breeding programmes. In the present study, quantum dots (QDs) were biofunctionalized with a specific antibody against P. betae. The glutathione-S-transferase protein's (GST) corresponding antibody (anti-GST) was effectively conjugated to Tioglicolicacid-modified Cadmium-Telluride QDs (CdTe-QDs) synthesized in an aqueous solution via electrostatic interaction. The dye (Rhodamine) molecules were attached to the GST. Donor-acceptor complexes (QDs-Ab-GST-Rhodamine) were then formed based on the antigen-antibody interaction. The mutual affinity of the antigen and the antibody brought the CdTeQDs and rhodamine together close enough to allow the resonance dipole-dipole coupling required for fluorescence resonance energy transfer (FRET) to occur. The immunosensor constructed showed a high sensitivity and specificity of 100%, acceptable stability and could be used for real sample detection with consistent results. To the best of our knowledge, this is the first report on designing a nano-based biosensing tool for the detection of plant pathogenic fungi.