New lateral flow immunoassay for on-site detection of Erwinia amylovora and its application on various organs of infected plants

Erwinia amylovora causes a quarantine disease called fire blight that affects most plants from the Rosaceae family. An efficient and rapid disease diagnosis tool is needed to prevent the spread of the pathogen. The main objective of this study was to develop a lateral flow immunoassay (LFIA) to detect E. amylovora and compare different organs of plants for optimization of LFIA testing. A total of 11 strains of E. amylovora and related species were tested for specificity of the developed LFIA. The detection limit of E. amylovora was equal to 4 × 105 CFU mL−1 in plant extracts. LFIA showed high specificity and did not demonstrate positive results with non-related species. Meanwhile, LFIA's effectiveness was confirmed through testing artificially infected leaf samples of apple, pear, and black raspberry. Reliable results were obtained 10 min after the start of LFIA for all testing strains. Different plant organs (121 samples) comprising apple, pear, hawthorn, quince, blackthorn, and cherry from naturally infected areas with symptoms of varying severity were tested. The LFIA was performed using samples from leaves, twigs, flowers, fruitlets, and bacterial ooze; for confirmation commercial kits based on fluorescent amplification–based specific hybridization PCR were used. Using several samples from one plant (cluster) significantly increased the accuracy of infected plant detection, the overlap of LFIA and PCR were equal to 70.2% for individual samples and 93.5% for clusters. Observed recovery of E. amylovora for different organs differed by up to 20%. We found out that using vascular tissues was better than using leaf extracts. This result demonstrates that LFIA's effectiveness improved when more appropriate samples were used. © 2021 Elsevier Ltd