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Pectobacterium brasiliense is a bacterial phytopathogen that causes soft and black rot and actively spreads worldwide. Our study is the first development of immunoassays for detecting P. brasiliense. We immunized rabbits and obtained serum with an extremely high titer (1:108). Isolated polyclonal antibodies were tested by enzyme-linked immunosorbent assay (ELISA) using 18 closely related strains and 5 non-related bacterial pathogens. No cross-reactivity was found concerning the tested pathogens. The ELISA of P. brasiliense was developed in a double-antibody sandwich format with a detection limit of 1.5 × 104 cells/mL. A lateral flow immunoassay (LFIA) for P. brasiliense was also developed in a double-antibody sandwich format with a detection limit of 1 × 105 cells/mL. The results of P. brasiliense cells testing with LFIA in plant matrix showed a high correlation (R2 = 0.932) between concentrations of added and revealed cells. When testing potato seed material, ELISA and LFIA confirmed 75 and 66% of positive samples according to real-time PCR, respectively. For negative samples, ELISA showed 84% coincidence, and LFIA coincided with PCR for 89% of samples. Thus, the developed immunoassays can be used to evaluate plant material in poorly equipped conditions or under field testing. [ABSTRACT FROM AUTHOR]

Rapid non-laboratory screening of plants for pathogenic viruses crucially influences crop yields in modern agricultural technologies. The aim of this study was to develop a highly-sensitive lateral flow immunoassay (LFIA) for rapid detection of potato leafroll virus (PLRV), an infectious agent of one of the most widespread potato diseases. The proposed LFIA combines the formation of sandwich immune complexes with gold nanoparticles (GNP) as labels and silver enhancement. The enhancement stage was realized using mixture of silver lactate and hydroquinone and subsequent addition of chloride-containing buffer to stop silver reduction. LFIA with silver enhancement was 15 times more sensitive (detection limit 0.2 ng/mL; 15 min) compared with conventional LFIA (detection limit 3 ng/mL; 10 min). The enhanced LFIA detected PLRV in leaves’ extracts of infected potato in dilutions higher than enzyme-linked immunosorbent assay. [ABSTRACT FROM AUTHOR]