Dipstick Assay Research Articles

Novel high-performance detection of Raillietina echinobothrida, Raillietina tetragona, and Raillietina cesticillus using loop-mediated isothermal amplification coupled with a lateral flow dipstick (LAMP-LFD)

Cestodes belonging to the genus Raillietina are a major veterinary health problem in the poultry industry, especially in chickens (Gallus gallus domesticus) and ducks (Anas playtrhynchos domesticus). In this study, loop-mediated isothermal amplification coupled with a lateral flow dipstick (LAMP-LFD) assay was established and validated for the detection of R. echinobothrida, R. tetragona, and R. cesticillus in one reaction. The LAMP-LFD assay can be completed in 75 min under isothermal conditions at 66 °C and the results can be obtained by observation with the naked eye. This assay was very specific and had no cross-amplification with other closely related parasites (Cotugnia sp., Diorchis formosensis, Fimbriaria sp., Echinostoma sp., E. miyagawai, Hypoderaeum conoideum, Prosthogonimus cuneatus, and Ascaridia galli) or their definitive hosts (G. g. domesticus, A. p. domesticus). The sensitivity of the LAMP-LFD assay was detected with three Raillietina species at 0.5 ng, which was enough for gravid proglottid DNA detection. The accuracy test showed that the LAMP-LFD assay demonstrated accurate verification results when compared to morphological results. This is a novel LAMP-LFD assay that is highly specific and sensitive for the detection of Raillietina species. It can be applied to detection for epidemiological investigations, monitoring programs, surveillance, control, and to solve veterinary health problems for the poultry industry in Raillietina endemic areas.

Development of a recombinase polymerase amplification combined with lateral flow dipstick assay for rapid and sensitive detection of bean common mosaic virus

Bean common mosaic virus (BCMV) is one of the most widespread and damaging viruses of cultivated legumes in the world. In addition to serious yield reduction and germplasm decline, BCMV infection also makes legumes more vulnerable to other pathogens. Early diagnosis of the virus is particularly important in limiting its spread. Recombinase polymerase amplification (RPA) is a novel isothermic amplification technology. The whole reaction can be done outside the laboratory environment after the nucleic acid sample is obtained. In this study, we established a rapid and sensitive RPA combined with the lateral flow dipstick (LFD) assay for detection of BCMV, based on the conserved BCMV coat protein (CP) gene sequence. Specific primers and a probe were designed, which amplify ~ 150 bp CP fragments from BCMV-infected samples under a constant temperature of 37 °C for 20 min. The end-labeled amplification products were detected by high-affinity LFD within 5 min. Sensitivity of this RPA-LFD assay was 1000 times greater than that of the conventional polymerase chain reaction (PCR) assay. Furthermore, when the primers/probe were used against related potyviruses including soybean mosaic virus (SMV), bean yellow mosaic virus (BYMV), and turnip mosaic virus (TuMV), the three potyviruses were not detected, indicating that the assay was BCMV species-specific. The RPA-LFD assay was also successfully applied for the detection of seed-borne BCMV in beans. The RPA-LFD assay has great potential application in the rapid diagnosis of BCMV in the field.

Recombinase-aided amplification–lateral flow dipstick assay—a specific and sensitive method for visual detection of avian infectious laryngotracheitis virus

The purpose of this study was to explore a specific, simple, and sensitive method for diagnosis of avian infectious laryngotracheitis virus. Recombinase-aided amplification (RAA) and lateral flow dipstick (LFD) were combined for labeling the optimized RAA probe with 6-carboxyfluorescein (FAM) and the 5′-end of the downstream primer with biotin, respectively. By optimizing the reaction time, temperature, and primer concentration of RAA, a RAA–LFD assay, which could be used for detection of infectious laryngotracheitis, was established. After the specificity and sensitivity test, the target gene fragments could be amplified by RAA–LFD assay in 20 min under isothermal conditions (37°C), and the amplification products could be visually observed and determined by LFD within 3 min. There was no cross-reaction with nucleic acids of other avian pathogens, the lowest detectable limit of RAA–LFD was 102 copies/μL, and the sensitivity of this method was 100 times higher than that of conventional PCR with the lowest detectable limit of 104 copies/μL. The results showed that RAA–LFD assay was highly sensitive, easy to use, and more suitable for clinical detection.

Development of a colorimetric paper fluidic dipstick assay for measurement of glycated albumin to monitor gestational diabetes at the point-of-care

Gestational diabetes mellitus (GDM) affects between 2 and 14% of pregnant women in the United States every year. Currently, glucose and hemoglobin A1c (HbA1c) are the standard biomarkers used to monitor GDM but HbA1c is representative of 2–3 months of glycemic data and is too infrequent for managing clinical impact of GDM while glucose provides multiple daily readings which arguably are not entirely necessary for mild to moderate GDM and often result in non-compliance from the patient's side. Thus, there is a need for an intermediate biomarker which can be used effectively to monitor the glycemic status of GDM patients. Serum albumin, the most abundant protein in blood, undergoes non-enzymatic glycation in the bloodstream. Owing to its half-life of ~21 days, it can effectively be used as an intermediate biomarker. Normal level of glycation of albumin is between 10 and 16% whereas in diabetic patients it is much higher, between 16 and 40%. Thus, a point-of-care (POC) monitoring system to detect glycated albumin (GA) as a % of total serum albumin has been developed here. Specifically, a dipstick paper fluidic test to measure % glycated albumin has been developed that used an aptamer assay with gold nanoparticles to produce colorimetric measurements. Both the glycated and unglycated versions of albumin were measured in their relevant physiological concentration ranges – 50 μM–300 μM with a limit of detection (LoD) of 6.5 μM for glycated albumin and 500 μM–750 μM with a LoD of 21 μM for unglycated serum albumin. The use of aptamers as recognition elements, instead of commonly used antibodies, not only provided the required sensitivity, specificity, and dynamic range but they also have the added advantage of being stable at room temperature for an extended period of time providing the potential for these dipstick tests to be used for GDM monitoring at the point-of-care (POC).

RAPID URINE TRYPSINOGEN-2 DIPSTICK ASSAY TO DIAGNOSE ACUTE PANCREATITIS IN EMERGENCY SETUP

Background: Early diagnosis of acute pancreatitis remains a challenge in emergency set up. The early management results in better outcomes but none of the available investigations were rapid and accurate to guide the management in these patients. Hence in suspected cases of acute pancreatitis, the urinary trypsinogen 2 dipstick assay can be used to diagnose them at the earliest in the Emergency setup. The purpose of this study is to determine the accuracy of urine trypsinogen 2 assay in diagnosing acute pancreatitis. Methods: The patients presenting with symptoms consistent with acute pancreatitis to the emergency department, at a tertiary care hospital in Southern India between November 2018 to November 2019 were included in a prospective observational study after obtaining Institutional ethical committee clearance. In addition to the routine investigations done in cases of acute abdomen, patients underwent urine trypsinogen 2 dipstick test. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) were calculated. Results were compared. Results: A total of 50 cases were included in the study. The urine trypsinogen 2 dipstick test was positive in 35 of 37 patients with acute pancreatitis (sensitivity, 94.59%) and in none of 13 patients with abdominal pain but without any evidence of acute pancreatitis (specificity, 100%). The diagnostic accuracy of the urine trypsinogen 2 dipstick test was 96% in this study higher than other conventional laboratory investigations. Conclusion: This study shows that the dipstick test has high diagnostic accuracy and can be considered for regular use for diagnosing pancreatitis along with the conventional methods.

Direct detection of methicillin-resistant in Staphylococcus spp. in positive blood culture by isothermal recombinase polymerase amplification combined with lateral flow dipstick assay.

Methicillin-resistant staphylococci (MRS) are important antimicrobial-resistant pathogens in sepsis. Conventional blood cultures take 24-72h. The polymerase chain reaction (PCR)-based methods give faster results (2-3h) but need expensive thermal cyclers. We therefore developed an isothermal recombinase polymerase amplification (RPA) combined with lateral flow dipstick (LFD) assay for rapid detection of MRS in spiked blood culture samples. Fifty-six clinical isolates including 38 mecA-carrying staphylococci and 18 non-mecA-carrying organisms as confirmed by PCR methods were studied. RPA primer set and probe specific for mecA gene (encoding penicillin-binding protein 2a) were designed. RPA reaction was carried out under isothermal condition (45°C) within 20min and read by LFD in 5min. The RPA-LFD provided 92.1% (35/38) sensitivity for identifying MRS in positive blood culture samples, and no cross-amplification was found (100% specificity). This test failed to detect three mecA-carrying S.sciuri isolates. The detection limits of RPA-LFD method for identifying MRS were equal to those of PCR method. The RPA-LFD is simple, fast, and user-friendly. This method could detect the mecA gene directly from the positive blood culture samples without requirement for special equipment. This method would be useful for appropriate antibiotic therapy and infection control, particularly in a low-resource setting.

Rapid visualization in the specific detection of Flavobacterium columnare, a causative agent of freshwater columnaris using a novel recombinase polymerase amplification (RPA) combined with lateral flow dipstick (LFD) assay

Flavobacterium columnare is the causative agent of columnaris, a serious disease affecting numerous freshwater fish species worldwide. Although several molecular protocols have been established to detect this pathogen, there still remains a need to develop simpler on-field applicable techniques. Here, we report a more practical and efficient assay to detect F. columnare based on the combination of recombinase polymerase amplification (RPA) and a lateral flow dipstick (LFD). The assay, as performed for 30 min at 37 °C for RPA, followed by 2 min at ambient temperature for LFD, revealed a comparable detection limit (200 fg total DNA and 0.4 CFU) to the PCR assay developed by Mabrok et al. in 2020 but required only ~35 min to complete tests (i.e. ~four times faster). Cross-reactivity against other bacteria and false results on 20 clinical samples were not observed, indicating its extremely high specificity and accuracy. The robust performance of the assay to crude tissue samples and clinical specimens reflect its potential use in field application/low-resource settings. The use of a fast and affordable DNA extraction kit is imperative as part of our assay to make the detection of F. columnare more feasible.

Melioidosis DS rapid test: A standardized serological dipstick assay with increased sensitivity and reliability due to multiplex detection.

BackgroundMelioidosis, caused by Burkholderia pseudomallei, is a severe infectious disease with high mortality rates, but is under-recognized worldwide. In endemic areas, there is a great need for simple, low-cost and rapid diagnostic tools. In a previous study we showed, that a protein multiplex array with 20 B. pseudomallei-specific antigens detects antibodies in melioidosis patients with high sensitivity and specificity. In a subsequent study the high potential of anti-B. pseudomallei antibody detection was confirmed using a rapid Hcp1 single protein-based assay. Our protein array also showed that the antibody profile varies between patients, possibly due to a combination of host factors but also antigen variations in the infecting B. pseudomallei strains. The aim of this study was to develop a rapid test, combining Hcp1 and the best performing antigens BPSL2096, BPSL2697 and BPSS0477 from our previous study, to take advantage of simultaneous antibody detection.Methods and principal findingsThe 4-plex dipstick was validated with sera from 75 patients on admission plus control groups, achieving 92% sensitivity and 97–100% specificity. We then re-evaluated melioidosis sera with the 4-plex assay that were previously misclassified by the monoplex Hcp1 rapid test. 12 out of 55 (21.8%) false-negative samples were positive in our new dipstick assay. Among those, 4 sera (7.3%) were Hcp1 positive, whereas 8 (14.5%) sera remained Hcp1 negative but gave a positive reaction with our additional antigens.ConclusionsOur dipstick rapid test represents an inexpensive, standardized and simple diagnostic tool with an improved serodiagnostic performance due to multiplex detection. Each additional band on the test strip makes a false-positive result more unlikely, contributing to its reliability. Future prospective studies will seek to validate the gain in sensitivity and specificity of our multiplex rapid test approach in different melioidosis patient cohorts.

Preliminary Development of a Competitive Fluorescent Quantum Dot-Based Immunochromatographic Test Strip for Sensitive Saxitoxin Detection

Rapid and portable detection of saxitoxin (STX) and its many congeners is highly desirable to prevent paralytic shellfish poisoning due to red tide or harmful algal blooms. In this work, we describe successful preliminary efforts to develop a very sensitive general STX family test strip employing highly fluorescent red quantum dots (Qdot 655) to detect as little as 0.5 to 1 part per billion (ppb or ng/ml) of STX with a dynamic range extending to 20,000 ppb after the prototype dipstick assay was optimized. A competitive format was necessitated by the small molecule nature of STXs having only one epitope, but the decrease in Qdot fluorescence was clearly visible to the naked eye as a function of increasing STX concentration in aqueous buffer. The competitive displacement assay format required conjugation of a primary amine in STX to carboxyl-Qdot 655 via a covalent carbodiimide coupling reaction which was validated by an electrophoretic mobility band shift assay.

Improvement of Loop-Mediated Isothermal Amplification Combined with Chromatographic Flow Dipstick Assay for Salmonella in Food Samples

Loop-mediated isothermal amplification (LAMP) had been employed as a powerful tool to facilitate genetic tests for various food pathogens, as it is easy to perform. Recently, various methods of detecting the LAMP amplicon were developed. In this study, we improved two LAMP assays by combining LAMP with chromatographic flow dipstick (LFD) assays for Salmonella (targeting phoP and invA, respectively). We evaluated different labeled primer sets, then selected the optimal sets to perform the LFD assays. We compared the optimal LFD and LAMP assays with the ISO standard method. The results showed that LFD was more sensitive and quicker than LAMP. Furthermore, enrichment broths of 225 food samples were tested. The sensitivity of two LFD assays was 100%. The specificity of LFD assay targeting phoP was 99.1%, and LFD assay targeting invA was 99.5%. For the LFD assay targeting phoP, the estimate of limit of detection (LOD) 50% was 0.061 CFU/g and the estimate of LOD 95% was 0.265 CFU/g. For the LFD assay targeting invA, the estimate of LOD 50% was 0.040 CFU/g and the estimate of LOD 95% was 0.172 CFU/g. We validated this method in a primary laboratory, where we accomplished the assay only using an incubator and a heating block. It suggested that the LFD assay had the potential to become a suitable diagnostic method in field test and primary labs.

Development of dipstick enzyme linked immunosorbent assay for on-site sero-diagnosis of Japanese encephalitis in swine

Japanese encephalitis (JE) is an important viral zoonotic disease in Asia, especially in rural and suburban areas where rice cultivation and pig farming coexist. Pigs serve as a suitable sentinel model, the surveillance of which could predict a potential JE outbreak in human population in the immediate vicinity. However, existing diagnostics like ELISA and VNT require sophisticated laboratory facilities which are more often not available in field conditions. In the present study, we aimed at developing recombinant non-structural (NS1) protein-based dipstick IgG ELISA as an on-site assay for sero-diagnosis of JE in swine. The assay was standardized by optimizing various parameters and the following conditions were found to be ideal including 1 μg of rNS1 protein in carbonate buffer per strip of nitrocellulose membrane comb; bovine serum albumin as blocking agent at 4 °C overnight; serum dilution of 1:10 and conjugate dilution of 1:5000 in skimmed milk powder. Relative diagnostic sensitivity and specificity of dipstick IgG ELISA was 100% and 92.9%, respectively. The dipstick assay was validated in three laboratories as per OIE guidelines. The storage life of dipstick was up to 7 months at 4 °C. The assay is easy to perform and the results can be interpreted with visual observation that precludes the need for absorbance reading equipment. The standardized dipstick assay was found promising for screening swine serum samples in field conditions. Timely detection of JE virus in swine will aid in predicting the outbreak in humans and thus in taking suitable preventive and control measures.

Rapid visual detection of dengue virus by combining reverse transcription recombinase-aided amplification with lateral-flow dipstick assay

ObjectivesDengue caused by infection with the dengue virus (DENV) is endemic in the tropical and subtropical regions of the world and of greatest public health concern. With more large outbreaks in rural areas, the purpose of this study was to develop a point-of-care test using recombinase-aided amplification and lateral-flow dipsticks for rapidly detecting DENV in low-resource settings. MethodsThe primers for the recombinase-aided amplification (RAA) assay were designed based on 3’ UTR of the DENV genome and screened. The RAA temperature, time and the concentration of primers were then optimized, as well as the lateral-flow dipstick assay (LFD) time. Finally, the diagnostic performance of the reverse transcription (RT)-RAA-LFD assay was evaluated using blood samples from 247 patients who were clinically suspected to be infected with DENV. ResultsThe RAA primer pair F1/R2 was the optimal combination for detecting DENV. The RT-RAA was performed in an incubator block at 37°C for 20minutes, and the amplicons were visible in the flow dipsticks from a naked eye within 3minutes. The detection limit of the developed RT-RAA-LFD assay was 10 copies/μL with high specificity for DENV. Compared with commercial reverse transcription quantitative PCR assay, the kappa value of RT-RAA-LFD in the 247 clinical samples was 0.957. ConclusionsIn this study, a rapid and visual point-of-care test based on RT-RAA and LFD assay was developed. It was found to be suitable for reliable detection of DENV in low-resource settings with limited laboratory capabilities and optimal storage conditions.

Field applicable detection of hepatitis B virus using internal controlled duplex recombinase-aided amplification assay and lateral flow dipstick assay.

Hepatitis B virus (HBV) is a widespread blood-borne pathogen associated with the complication of liver cirrhosis and hepatocellular carcinoma, particularly in south-east Asian and African countries where HBV is highly endemic and the budget and resources are limited. Therefore, simple, rapid, and portable field detection methods are crucial to efficiently control HBV infection. In this study, using heat-treated DNA, we developed two-field applicable detection assays for HBV based on recombinase-aided amplification (RAA). One was an internal controlled duplex RAA assay using a portable real-time fluorescence detection device, another was an instrument-free visual observation assay using lateral flow dipsticks. The entire experimental time was greatly shortened to less than 40 minutes at 39.0°C. The sensitivities, specificities, and clinical performance of both assays were evaluated. Compared with quantitative polymerase chain reaction assay as a reference, our results demonstrated that the two RAA-based assay obtained 97.18% and 95.77% of sensitivity, respectively, and the specificity was 100%, by testing a total of 157 serum samples with HBsAg positive. We conclude that the advantages of rapidity, simplicity, portability, and visualization of proposed two assays make them great potentials in point-of-care testing of HBV infection by untrained people in resource-limited situations.

New Development of Disaster-Related and Tropical Infectious Diseases Control

As described in Japanese essay (Hojoki), written around 1200, various disasters such as big fires, earthquakes, and famines have occurred in Japan. Asian countries have been suffering from the disasters; furthermore, natural disasters are increasing due to global warming. Because tropical-infectious diseases are often disaster-related infectious diseases (DRIDs), the strategies against the former kind of disease could be applicable to DRIDs. Meteorological analysis of the occurrence of DRIDs using a method of time series analysis is important. In situations of disasters, it is desirable if you can identify the pathogen and identify disease severity simultaneously. A dipstick DNA chromatography assay termed as Single-Tag Hybridization—Printed Array Strip (STH—PAS) system was developed based on the DNA sequences of various mosquito-borne diseases. The plasma levels of matricellular proteins including galectin-9 (Gal-9) and osteopontin (OPN) were found to reflect the disease severities in the dengue virus and other DIRDs. Because both proteins have been reported to be immune-check molecules, their inhibition might enhance the immune system against pathogens. We found that brefelamide derivatives could inhibit OPN and other inflammatory molecules synthesis. Very recently, different derivatives were found to inhibit PD-L1 transcription. Applications of these agents should be considered as multi-step strategies against DRIDs.

Improvement and evaluation of loop-mediated isothermal amplification combined with chromatographic flow dipstick assays for Vibrio parahaemolyticus

Vibrio parahaemolyticus, a major food-borne pathogen, is a gram-negative rod-shaped halophilic bacterium which inhabits marine environments throughout the world. It can pose a threat to humans after the consumption of raw or undercooked seafood. Fast detection is crucial for hindering and controlling V. parahaemolyticus infection. Compared with traditional methods, loop-mediated isothermal amplification (LAMP) is a simple, rapid and versatile method. It can be performed at one temperature without the need for cycling. As a new method in recent years, LAMP combined with a chromatographic flow dipstick (LFD) meets the needs of point-of-care testing without the need for special instruments. It avoids the limitations of LAMP, reduces detection time and increases detection accuracy. Our previous studies have suggested that the optimized LFD method can improve the sensitivity of LAMP detection and shorten the isothermal amplification time during the detection process. In the present study, two LAMP assays were improved to LFD methods, and a LFD targeting 16S23S rRNA gene internal transcribed spacer (ITS) of V. parahaemolyticus was developed. The lower limit for tlh, toxR, ITS LFD assays were detected as 3.1 × 100, 3.1 × 101, and 3.1 × 100 CFU respectively, whether in pure cultures or artificially contaminated food samples. The shortest amplification times at the limit of each assay were determined as 20 min, 35 min and 25 min. A heating block was used to perform two (tlh and ITS) LFD assays to detect 20 food samples. Compared to a standard method (GB 4789.7–2013 National Food Safety Standards, Food Microbiology Inspection, Vibrio parahaemolyticus test), tlh and ITS LFD assays showed more MPN (most probable number) results than that of culture. It demonstrated that the improved LFD technology can provide a simple and rapid detection method with high sensitivity and specificity for detection of V. parahaemolyticus.

Sorbent-incorporated dipstick for direct assaying of proteases.

Efficient removal of interferents from complex matrices would significantly improve the performance of state of the art dipstick assays. Herein, we evaluate a graphitized carbon black (GCB)-incorporated dipstick, a configuration that has not been explored before, for reliable and facile on-site analysis of complex matrices. Carrot juice, a highly pigmented sample matrix, is chosen for evaluating the retention of interferents within the sorbent-incorporated cleanup pad on the dipstick. A peptide with a specific cleavage site for botulinum neurotoxin A light chain (BoNT/A LC), a model protease for validation of the proposed dipstick assay, is incubated with the test samples containing BoNT/A LC. Subsequently, the BoNT/A LC digested substrate and sample matrix flow vertically through the GCB-deposited cleanup pad within which the matrix interferents are captured, while the substrate, with a minimum of interferents, continues to flow toward a conjugation pad for labelling with Europium particles. Finally, the cleaved and uncleaved substrates flow toward a detection zone, where they bind to the test line producing a pinkish band which is not visible in the absence of GCB incorporation. The dipstick assay yields a LOD of 0.1nM (5ng/mL) of BoNT/A LC in carrot juice, within 20min. The reported approach enables detection of proteases in a wide range of matrices upon incorporation of appropriate sorbents, ultimately aiming to exclude tedious laboratory-based sample pre-treatment protocols. Thus, merging extraction, cleanup, and pre-concentration steps with a sensitive optical detection approach is an attractive strategy for on-site assaying in complex matrices. Graphical abstract.

Visual and rapid detection of Plesiomonas shigelloides using loop-mediated isothermal amplification method.

Plesiomonas shigelloides is a common pathogen of aquatic animals and can pose a certain hazard to aquaculture. Here, we aimed to develop a loop-mediated isothermal amplification (LAMP) method for the visual detection of P. shigelloides to aid the diagnosis of infections caused by this pathogen in aquatic animals. We used LAMP to amplify P. shigelloides DNA and combined it with calcein or nucleic acid dipstick assay (NADA) to visualize the amplified products. The optimal LAMP amplification temperature was 64°C, and the reaction lasted for 50min. The limit of detection of recombinant plasmids containing the target gene using the LAMP method was 2·0×102 copies per μl, which is ten times higher than that using conventional polymerase chain reaction (PCR). LAMP products could be visualized without agarose gel electrophoresis. We tested 85 fish specimens using the established LAMP method and conventional PCR. The detection rate was 42·4% using the LAMP method and 34·1% using conventional PCR. Based on our results, the LAMP method combined with calcein or NADA is a rapid, specific, sensitive and accurate method for visual detection of fish-derived P. shigelloides and can be used for the laboratory diagnosis of infections caused by it. SIGNIFICANCE AND IMPACT OF THE STUDY: The combination of loop-mediated isothermal amplification (LAMP) and calcein and nucleic acid dipstick assay (NADA) provided a rapid, specific and sensitive method for detecting Plesiomonas shigelloides, which is an important pathogen that causes diseases in aquatic animals worldwide. In the present study, the LAMP method showed a higher detection rate than conventional PCR for P. shigelloides using templates from 85 fish specimens. Thus, the LAMP method could be a reliable and convenient tool for diagnosing diseases in aquatic animals in the laboratory.

Transgenic potato lines expressing CP4-EPSP synthase exhibit resistance against glyphosate

Potato crops are particularly vulnerable to weed competition from emergence to canopy closure and are subject to significant yield loss. Glyphosate is broad spectrum herbicide used to control weeds worldwide. In order to incorporate glyphosate resistant trait in four potato cultivars (Lady Olympia, Desiree, Agria and Granola), an efficient, cost effective, reproducible and stable Agrobacterium-mediated genetic transformation protocol was performed using leaf and internodal explants. Agrobacterium strain LBA4404 harboring newly modified recombinant binary vector pCAMHE-EPSPS containing EPSP synthase gene under the control of Cauliflower mosaic virus 35S promoter was used to infect explants. The overall transformation efficiency was 26.4%. Of the 280 plants transferred to greenhouse, 74 plants were found to be PCR positive with gene of interest. GUS histochemical, Southern blot, RT-qPCR, lateral flow dipstick assays confirmed integration and expression of EPSPS in primary transformants. The putative transgenic plants developed from these cultivars possessed enhanced resistance to glyphosate applications in T0 and first tuber generation. These transgenic potato lines could be used as source of germplasm for an efficient potato breeding program. The article reports the development of potato transgenic lines with enhanced tolerance against glyphosate.

Embryo select assay: a non-invasive, dipstick elisa strip assay to identify the most competent embryo from the cohort

Embryo select assay: a non-invasive, dipstick elisa strip assay to identify the most competent embryo from the cohort

Comparative Evaluation of a Novel Recombinase Polymerase Amplification-Lateral Flow Dipstick (RPA-LFD) Assay, LAMP, Conventional PCR, and Leaf-Disc Baiting Methods for Detection of Phytophthora sojae.

Early and accurate detection of the causal pathogen Phytophthora sojae is crucial for effective prevention and control of root and stem rot and seedling damping-off of soybean. In the present study, a novel isothermal amplification assay was developed for detecting P. sojae. This 25 min assay included a two-step approach. First, a pair of novel primers, PSYPT-F and PSYPT-R were used to amplify a specific fragment of the Ypt1 gene of P. sojae in a 20 min recombinase polymerase amplification (RPA) step. Second, lateral flow dipsticks (LFD) were used to detect and visualize RPA amplicons of P. sojae within 5 min. This RPA-LFD assay was specific to P. sojae. It yielded negative detection results against 24 other Phytophthora, one Globisporangium, and 14 fungal species. It was also found to be sensitive, detecting as low as 10 pg of P. sojae genomic DNA in a 50-μL reaction. Furthermore, P. sojae was detected from artificially inoculated hypocotyls of soybean seedlings using this novel assay. In a comparative evaluation using 130 soybean rhizosphere samples, this novel assay consistently detected P. sojae in 55.4% of samples, higher than other three methods, including loop-mediated isothermal amplification (54.6%), conventional PCR (46.9%), and leaf-disc baiting (38.5–40.0%). Results in this study indicated that this rapid, specific, and sensitive RPA-LFD assay has potentially significant applications to diagnosing Phytophthora root and stem rot and damp-off of soybean, especially under time- and resource-limited conditions.