Comparative evaluation of lateral flow immunoassays, LAMP, and quantitative PCR for diagnosis of fire blight in apple orchards

Abstract

Fire blight remains a serious threat to commercial apple production in the USA and worldwide. Other diseases and spray damage can result in fire blight-like symptoms that can lead to misdiagnosis and affect disease management strategies. Accurate and timely detection of the fire blight pathogen, Erwinia amylovora, is extremely important to deploy appropriate and timely measures to reduce fire blight epidemics in commercial apple orchards. We tested two commercial lateral flow immunoassays (AgriStrip®, and Pocket Diagnostics kit), Loop mediated isothermal amplification (LAMP), and quantitative PCR (qPCR) to diagnose E. amylovora infected samples in lab and field settings. The AgriStrip® and Pocket Diagnostics kits were able to detect actively growing bacteria up to ×10 6 cfu/ml bacterial concentration. Pocket Diagnostics kit had less specificity and showed positive tests for E. pyrifolia in addition to E. amylovora. The LAMP assay showed high specificity for E. amylovora and was able to detect up to ×10 3 cfu/ml bacterial concentrations. The qPCR assay was also able to detect bacterial cells up to ×10 −3 cfu/ ml bacterial concentration with highly specific E. amylovora detection. Grower surveys and comparative cost-benefit analysis indicated that immunoassay kits are less expensive, easier to use, and require less technical expertise for on-site fire blight diagnosis than LAMP and qPCR. However, the choice of a specific diagnostic assay depends on the time, sensitivity, and specificity required for the detection of fire blight and its management.

Identification of Phytoplasmas Representing Multiple New Genetic Lineages from Phloem-Feeding Leafhoppers Highlights the Diversity of Phytoplasmas and Their Potential Vectors

“…Similarity coefficients derived from virtual RFLP analysis of 16S rRNA genes of strain PLH102-1 and other 16SrI subgroups were less than or equal to 0.97, the threshold for a new subgroup delineation [ 26 ]. Therefore, strain PLH102-1 was designated as a new subgroup 16SrI-AO ( Table 2 [ 10 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 ], some of previously reported 16SrI subgroups were reassigned due to duplication).…”

CRISPR genotyping as complementary tool for epidemiological surveillance of Erwinia amylovora outbreaks

“…However, it is inefficient to inform about pathogenicity and virulence of E. amylovora, attending that genetic determinants of pathogenicity and virulence are located in distinct genomic regions (e.g., plasmids; pathogenicity genomic islands). Therefore, these determinants are exposed to distinct selective pressures and consequently to distinct evolutionary dynamics as emphasized by comprehensive comparative and functional genomics studies (as reviewed by Llop et al, [76]; Llop,[77]; Yuan et al, [78]). Despite genetic differences between E. amylovora strains showing distinct virulence phenotypes being reported, the genomic landscape responsible for a higher or lower virulence is still unknown as emphasized previously [36].…”

Biosensor Technologies for Early Detection and Quantification of Plant Pathogens

“…Another main factor is affordability—massive reduction in cost per sample within nano-biosensor devices has already been achieved using bare screen-printed carbon electrodes ($2.50 USD per test) and streptavidin coated screen-printed carbon electrodes ($5 USD per test) ( Lau et al, 2017 ). The commercial AgriStrip™ and Pocket Diagnostic kits cost <$10 USD per sample ( Singh et al, 2020 ), although these are not quantitative. There remains an immediate need to develop equally sensitive and specific affordable biosensor diagnostic devices that are quantitative and that are able to detect multiple targets in a single assay, for accurate and truly informed disease management decision support.…”