Development of high-throughput quantum dot biosensor against Polymyxa species.

The plasmodiophoromycete Polymyxa betae and P. graminis are eukaryotic biotrophic parasites residing in the roots of chenopodiacae and gramineae plants. They are natural transmitting agents of several important plant viruses such as are beet necrotic yellow vein virus (BNYW), beet soil borne mosaic virus (BSBMV), wheat soil-borne mosaic virus (WSBMV). Developing advanced high-throughput diagnostic methods capable of accurate detection of these pathogens could assist with the screening programs and consequently with the development of disease-resistant germplasms. In the present study, a previously developed quantum dots (QDs) FRET-based nano-biosensor was upgraded to a high-throughput version. QDs were functionalized with a specific antibody against the P. betae's specific glutathione-S-transferase (GST) protein. On the other hand, GST was conjugated to Rhodamine dye. Ninety six-well polystyrene plates were used as the detection platform. The mutual affinity of the antigen and the antibody brought the CdTe QDs 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%, and was successfully used for high-throughput screening of 96 real samples with consistent results within the course of less than 30 minutes.

Antibody-mediated resistance against plant pathogens.

Plant diseases have a significant impact on the yield and quality of crops. Many strategies have been developed to combat plant diseases, including the transfer of resistance genes to crops by conventional breeding. However, resistance genes can only be introgressed from sexually-compatible species, so breeders need alternative measures to introduce resistance traits from more distant sources. In this context, genetic engineering provides an opportunity to exploit diverse and novel forms of resistance, e.g. the use of recombinant antibodies targeting plant pathogens. Native antibodies, as a part of the vertebrate adaptive immune system, can bind to foreign antigens and eliminate them from the body. The ectopic expression of antibodies in plants can also interfere with pathogen activity to confer disease resistance. With sufficient knowledge of the pathogen life cycle, it is possible to counter any disease by designing expression constructs so that pathogen-specific antibodies accumulate at high levels in appropriate sub-cellular compartments. Although first developed to tackle plant viruses and still used predominantly for this purpose, antibodies have been targeted against a diverse range of pathogens as well as proteins involved in plant-pathogen interactions. Here we comprehensively review the development and implementation of antibody-mediated disease resistance in plants.