Name: detection of phytophthora capsici in irrigation water using loop-mediated isothermal amplification
Uploaded: 2020-06-25T13:00:00
Description: Watch this Scientific Journal Video about Detection of Phytophthora capsici in Irrigation Water using Loop-Mediated Isothermal Amplification at JoVE.com

This work received the financial support of Georgia Commodity Commission for Vegetables project ID# FP00016659. The authors thank Dr. Pingsheng Ji, University of Georgia and Dr. Anne Dorrance, Ohio State University for providing pure cultures of Phytophthora spp. We also thank Li Wang and Deloris Veney for their technical assistance throughout the study.

1. On-site detection of Phytophthora capsici from irrigation water using portable loop-mediated isothermal amplification
<ol>
	<li>Setting up the pump and filter
	<ol>
		<li>Attach a filtering flask to a tube that is connected to a hand pump so that when the pump is activated, air will be pulled in through the mouth of the filtering flask.</li>
		<li>Fit the Buchner funnel into the rubber stopper to the mouth of the filtering flask and fit the appropriately sized piece of filter paper into the Buchner funnel s...

<ol>
	<li>Hong, C., Moorman, G. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plant+pathogens+in+irrigation+water:+challenges+and+opportunities.">Plant pathogens in irrigation water: challenges and opportunities.</a> Critical Reviews in Plant Sciences. 24 (3), 189-208 (2005).</li><li>Malkawi, H. I., Mohammad, M. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Physiology,+Genetics,+Morphology,+&amp;+Microorganisms,+E.+o.+Survival+and+accumulation+of+microorganisms+in+soils+irrigated+with+secondary+treated+wastewater.">Physiology, Genetics, Morphology, &amp; Microorganisms, E. o. Survival and accumulation of microorganisms in soils irrigated with secondary treated wastewater.</a> Journal of Basic Microbiology. 43 (1), 47-55 (2003).</li><li>Bush, E. A., Hong, C., Stromberg, E. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Fluctuations+of+Phytophthora+and+Pythium+spp.+in+components+of+a+recycling+irrigation+system.">Fluctuations of Phytophthora and Pythium spp. in components of a recycling irrigation system.</a> Plant Disease. 87 (12), 1500-1506 (2003).</li><li>Ghimire, S. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distribution+and+diversity+of+Phytophthora+species+in+nursery+irrigation+reservoir+adopting+water+recycling+system+during+winter+months.">Distribution and diversity of Phytophthora species in nursery irrigation reservoir adopting water recycling system during winter months.</a> Journal of Phytopathology. 159 (11-12), 713-719 (2011).</li><li>Hausbeck, M. K., Lamour, K. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Phytophthora+capsici+on+vegetable+crops:+research+progress+and+management+challenges.">Phytophthora capsici on vegetable crops: research progress and management challenges.</a> Plant Disease. 88 (12), 1292-1303 (2004).</li><li>Gevens, A., Donahoo, R., Lamour, K., Hausbeck, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+Phytophthora+capsici+from+Michigan+surface+irrigation+water.">Characterization of Phytophthora capsici from Michigan surface irrigation water.</a> Phytopathology. 97 (4), 421-428 (2007).</li><li>Thomson, S., Allen, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Occurrence+of+Phytophthora+species+and+other+potential+plant+pathogens+in+recycled+irrigation+water.">Occurrence of Phytophthora species and other potential plant pathogens in recycled irrigation water.</a> Plant Disease Reporter. 58 (10), 945-949 (1974).</li><li>Lamour, K. H., Stam, R., Jupe, J., Huitema, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+oomycete+broad-host-range+pathogen+Phytophthora+capsici.">The oomycete broad-host-range pathogen Phytophthora capsici.</a> Journal of Molecular Plant Pathology. 13 (4), 329-337 (2012).</li><li>Sanogo, S., Ji, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Water+management+in+relation+to+control+of+Phytophthora+capsici+in+vegetable+crops.">Water management in relation to control of Phytophthora capsici in vegetable crops.</a> Agricultural Water Management. 129, 113-119 (2013).</li><li>Zhang, Z., Li, Y., Fan, H., Wang, Y., Zheng, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Molecular+detection+of+Phytophthora+capsici+in+infected+plant+tissues,+soil+and+water.">Molecular detection of Phytophthora capsici in infected plant tissues, soil and water.</a> Plant Pathology. 55 (6), 770-775 (2006).</li><li>Trout, C., Ristaino, J., Madritch, M., Wangsomboondee, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+detection+of+Phytophthora+infestans+in+late+blight-infected+potato+and+tomato+using+PCR.">Rapid detection of Phytophthora infestans in late blight-infected potato and tomato using PCR.</a> Plant Disease. 81 (9), 1042-1048 (1997).</li><li>Sankaran, S., Mishra, A., Ehsani, R., Davis, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+review+of+advanced+techniques+for+detecting+plant+diseases.">A review of advanced techniques for detecting plant diseases.</a> Commputers and Electronics in Agriculture. 72 (1), 1-13 (2010).</li><li>Wang, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+an+improved+isolation+approach+and+simple+sequence+repeat+markers+to+characterize+Phytophthora+capsici+populations+in+irrigation+ponds+in+southern+Georgia.">Development of an improved isolation approach and simple sequence repeat markers to characterize Phytophthora capsici populations in irrigation ponds in southern Georgia.</a> Applied and Environmental Microbiology. 75 (17), 5467-5473 (2009).</li><li>Ali-Shtayeh, M., MacDonald, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Occurrence+of+Phytophthora+species+in+irrigation+water+in+the+Nablus+area+(West+Bank+of+Jordan).">Occurrence of Phytophthora species in irrigation water in the Nablus area (West Bank of Jordan).</a> Phytopathologia Mediterranea. , 143-150 (1991).</li><li>Pringsh, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparison+of+serological+and+culture+plate+methods+for+detecting+species+of+Phytophthora,+Pythium,+and+Rhizoctonia+in+ornamental+plants.">Comparison of serological and culture plate methods for detecting species of Phytophthora, Pythium, and Rhizoctonia in ornamental plants.</a> Plant Disease. 74 (9), 655 (1990).</li><li>Stewart-Wade, S. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Plant+pathogens+in+recycled+irrigation+water+in+commercial+plant+nurseries+and+greenhouses:+their+detection+and+management.">Plant pathogens in recycled irrigation water in commercial plant nurseries and greenhouses: their detection and management.</a> Irrigation Science. 29 (4), 267-297 (2011).</li><li>Aragaki, M., Uchida, J. Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Morphological+distinctions+between+Phytophthora+capsici+and+P.+tropicalis+sp.+nov.">Morphological distinctions between Phytophthora capsici and P. tropicalis sp. nov.</a> Mycologia. 93 (1), 137-145 (2001).</li><li>Tomlinson, J., Boonham, N. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Potential+of+LAMP+for+detection+of+plant+pathogens.">Potential of LAMP for detection of plant pathogens.</a> CAB Reviews Perspectives in Agriculture Veterinary Science Nutrition and Natural Resources. 3 (066), 1-7 (2008).</li><li>Li, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+PCR-based+assay+for+distinguishing+between+A1+and+A2+mating+types+of+Phytophthora+capsici.">A PCR-based assay for distinguishing between A1 and A2 mating types of Phytophthora capsici.</a> Journal of the American Society for Horticultural Science. 142 (4), 260-264 (2017).</li><li>Dong, Z., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Loop-mediated+isothermal+amplification+assay+for+sensitive+and+rapid+detection+of+Phytophthora+capsici.">Loop-mediated isothermal amplification assay for sensitive and rapid detection of Phytophthora capsici.</a> Canadian Journal of Plant Pathology. 37 (4), 485-494 (2015).</li><li>Khan, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+evaluation+of+the+LAMP+assay+and+PCR-based+assays+for+the+rapid+detection+of+Alternaria+solani.">Comparative evaluation of the LAMP assay and PCR-based assays for the rapid detection of Alternaria solani.</a> Frontiers in Microbiology. 9, 2089 (2018).</li><li>Sowmya, N., Thakur, M., Manonmani, H. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Rapid+and+simple+DNA+extraction+method+for+the+detection+of+enterotoxigenic+Staphylococcus+aureus+directly+from+food+samples:+comparison+of+PCR+and+LAMP+methods.">Rapid and simple DNA extraction method for the detection of enterotoxigenic Staphylococcus aureus directly from food samples: comparison of PCR and LAMP methods.</a> Journal of Applied Microbiology. 113 (1), 106-113 (2012).</li><li>Waliullah, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Comparative+analysis+of+different+molecular+and+serological+methods+for+detection+of+Xylella+fastidiosa+in+blueberry.">Comparative analysis of different molecular and serological methods for detection of Xylella fastidiosa in blueberry.</a> PLOS ONE. 14 (9), 0221903 (2019).</li><li>B&#246;hm, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+quantitative+PCR:+DNA+determination+in+isolated+spores+of+the+mycorrhizal+fungus+Glomus+mosseae+and+monitoring+of+Phytophthora+infestans+and+Phytophthora+citricola+in+their+respective+host+plants.">Real-time quantitative PCR: DNA determination in isolated spores of the mycorrhizal fungus Glomus mosseae and monitoring of Phytophthora infestans and Phytophthora citricola in their respective host plants.</a> Journal of Phytopathology. 147, 409-416 (1999).</li><li>Klimczak, L., Prell, H. J. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Isolation+and+characterization+of+mitochondrial+DNA+of+the+oomycetous+fungus+Phytophthora+infestans.">Isolation and characterization of mitochondrial DNA of the oomycetous fungus Phytophthora infestans.</a> Current Genetics. 8 (4), 323-326 (1984).</li><li>Ghimire, S. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+of+Phytophthora+species+in+a+run-off+water+retention+basin+at+a+commercial+nursery+in+plant+hardiness+zones+7+b+of+Virginia+in+winter.">Detection of Phytophthora species in a run-off water retention basin at a commercial nursery in plant hardiness zones 7 b of Virginia in winter.</a> Phytopathology. 96 (6), (2006).</li><li>Feng, W., Hieno, A., Kusunoki, M., Suga, H., Kageyama, K. J. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=LAMP+detection+of+four+plant-pathogenic+oomycetes+and+its+application+in+lettuce+fields.">LAMP detection of four plant-pathogenic oomycetes and its application in lettuce fields.</a> Plant Disease. 103 (2), 298-307 (2019).</li><li>Aglietti, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Real-time+loop-mediated+isothermal+amplification:+an+early-warning+tool+for+quarantine+plant+pathogen+detection.">Real-time loop-mediated isothermal amplification: an early-warning tool for quarantine plant pathogen detection.</a> AMB Express. 9 (1), 50 (2019).</li><li>Almasi, M. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+a+colorimetric+loop-mediated+isothermal+amplification+assay+for+the+visual+detection+of+Fusarium+oxysporum+f.+sp.+melonis.">Development of a colorimetric loop-mediated isothermal amplification assay for the visual detection of Fusarium oxysporum f. sp. melonis.</a> Horticultural Plant Journal. 5 (3), 129-136 (2019).</li><li>Gill, D. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pathogenic+Pythium+from+irrigation+ponds.">Pathogenic Pythium from irrigation ponds.</a> Plant Disease Reporter. 54 (12), 1077-1079 (1970).</li></ol>

The testing of irrigation water for phytopathogens is a crucial step for growers using irrigation ponds and recycled water27. Irrigation ponds provide a reservoir and breeding ground for a number of phytopathogens as excess irrigation water is directed from the field to the pond carrying with it any pathogens that may have been present16,27. The traditional method for detection of a plant pathogens in a large water source is to set a bait ...

Recycling water in farms and nurseries is becoming increasingly popular due to the increase in water costs and environmental concerns behind water usage. Many irrigation methods have been developed for growers to reduce the spread and occurrence of plant disease. Regardless of the source of the water (irrigation or precipitation), runoff is generated, and many vegetable and nursery growers have a pond to collect and recycle runoff1. This creates a reservoir for possible pathogen accumulation favoring the spread of pathogens when the recycled water is used to irrigate crops2,3,4. Oomycete plant pathogens particularly benefit from this practice as zoospores will accumulate in water and the primary dispersive spore is self-motile but requires surface water5,6,7. Phytophthora capsici is an oomycete pathogen that affects a significant number of solanaceous and cucurbit crops in different ways8. Often, the symptoms are damping-off of seedlings, root and crown rot; however, in crops such as cucumber, squash, melon, pumpkin, watermelon, eggplant and pepper, entire harvests may be lost due to fruit rot9. Although there are known methods of detecting this plant pathogen, most require an infection to have already taken place which is too late for any preventative fungicides to have a significant effect10.
The traditional method to test irrigation water for the detection and diagnosis of targeted microorganisms is an antiquated approach when speed and sensitivity are crucial to success and profitable crop production11,12. Plant tissue susceptible to the targeted pathogen (e.g., eggplant for P. capsici) is attached to a modified trap that is suspended in an irrigation pond for extended period before being removed and inspected for infection. Samples from the plant tissue are then plated on semi-selective media (PARPH) and incubated for culture growth, then morphological identification is performed using a compound microscope13. There are other similar detection methods for other plant pathogens using selective media and plating small amounts of contaminated water before sub-culturing14,15. These methods require anywhere from 2 to 6 weeks, several rounds of sub-culturing to isolate the organism, and experience on Phytophthora diagnostics to be able to recognize the key morphological characters of each species. These traditional methods do not work well for detection of irrigation water contaminated by P. capsici due to factors such as interference by other microorganisms that are also present in the water sources. Some fast-growing microorganisms like Pythium spp. and water-borne bacteria can overgrow on the plate making P. capsici undetectable16,17.
The purpose of this study was to develop a sensitive and specific molecular method that can be used in both field and laboratory settings to detect P. capsici zoospores in irrigation water. The protocol includes the development of a novel loop-mediated isothermal amplification (LAMP) primer set able to specifically amplify P. capsici, based on a 1121-base pair (bp) fragment of P. capsici18,19. A previously developed LAMP primer from Dong et al. (2015) was used in comparison to the assay that was developed for this study20.
The LAMP assay is a relatively new form of molecular detection that has been demonstrated to be more rapid, sensitive, and specific than conventional polymerase chain reaction (PCR)21. In general, conventional PCR assays cannot detect under 500 copies (1.25 pg/&#181;L); in contrast, previous studies have shown that the sensitivity of LAMP can be 10 to 1,000 times higher than conventional PCR and can easily detect even 1 fg/&#181;L of genomic DNA22,23. Additionally, the assay can be carried out rapidly (often in 30 min) and on-site (in the field) by using a portable heating block for amplification and a colorimetric dye that changes color for a positive sample (removing the need for electrophoresis). In this study, we compared the sensitivity of PCR and LAMP assays using a filter extraction method. The proposed detection method allows researchers and extension agents to easily detect the presence of P. capsici spores from different water sources in less than two hours. The assay is proven to be more sensitive than conventional PCR and was validated in situ by detecting the presence of the pathogen in the irrigation water used by a grower. This detection method will allow growers to estimate the presence and population density of the pathogen in various water sources that are being used for irrigation, preventing devastating outbreaks and economic losses.

<table>
	<tbody>
		<tr>
			<td>Agarose gel powder</td>
			<td>Thomas Scientific</td>
			<td>C997J85</td>
			<td></td>
		</tr>
		<tr>
			<td>Buchner funnel</td>
			<td>Southern Labware</td>
			<td>JBF003</td>
			<td></td>
		</tr>
		<tr>
			<td>Bullet Blender</td>
			<td>Next Advance</td>
			<td>BBX24</td>
			<td></td>
		</tr>
		<tr>
			<td>Centrifuge 5430</td>
			<td>Eppendorf</td>
			<td>22620509</td>
			<td></td>
		</tr>
		<tr>
			<td>Chloroform</td>
			<td>Fischer Scientific</td>
			<td>C298-500</td>
			<td></td>
		</tr>
		<tr>
			<td>CTAB solution</td>
			<td>Biosciences</td>
			<td>786-565</td>
			<td></td>
		</tr>
		<tr>
			<td>Dneasy Extraction Kit</td>
			<td>Qiagen</td>
			<td>69104</td>
			<td></td>
		</tr>
		<tr>
			<td>Filter Flask</td>
			<td>United</td>
			<td>FHFL1000</td>
			<td></td>
		</tr>
		<tr>
			<td>Filter Paper</td>
			<td>United Scientific Supplies</td>
			<td>FPR009</td>
			<td></td>
		</tr>
		<tr>
			<td>Gel Green 10000X</td>
			<td>Thomas Scientific</td>
			<td>B003B68 (1/EA)</td>
			<td></td>
		</tr>
		<tr>
			<td>Genie III</td>
			<td>OptiGene</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Hand pump</td>
			<td>Thomas Scientific</td>
			<td>1163B06</td>
			<td></td>
		</tr>
		<tr>
			<td>Iso-amyl Alcohol</td>
			<td>Fischer Scientific</td>
			<td>BP1150-500</td>
			<td></td>
		</tr>
		<tr>
			<td>LAVA LAMP master mix</td>
			<td>Lucigen</td>
			<td>30086-1</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnetic bead DNA extraction</td>
			<td>Genesig</td>
			<td>genesigEASY-EK</td>
			<td></td>
		</tr>
		<tr>
			<td>Magnetic Separator</td>
			<td>Genesig</td>
			<td>genesigEASY-MR</td>
			<td></td>
		</tr>
		<tr>
			<td>polyvinylpyrrolidone</td>
			<td>Sigma Aldrich</td>
			<td>PVP40-500G</td>
			<td></td>
		</tr>
		<tr>
			<td>Primers</td>
			<td>Sigma Aldrich</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Prism Mini Centrifuge</td>
			<td>Labnet</td>
			<td>C1801</td>
			<td></td>
		</tr>
		<tr>
			<td>T100 Thermal Cycler</td>
			<td>Bio-Rad</td>
			<td>1861096</td>
			<td></td>
		</tr>
		<tr>
			<td>UV Gel Doc</td>
			<td>Analytik Jena</td>
			<td>849-00502-2</td>
			<td></td>
		</tr>
		<tr>
			<td>Warmstart Colorimetric Dye</td>
			<td>Lucigen</td>
			<td>E1800m</td>
			<td></td>
		</tr>
		<tr>
			<td>Wide Mini ReadySub-Cell GT Cell</td>
			<td>Bio-Rad</td>
			<td>1704489EDU</td>
			<td></td>
		</tr>
		<tr>
			<td>70% isopropanol</td>
			<td>Fischer Scientific</td>
			<td>A451-1</td>
			<td></td>
		</tr>
	</tbody>
</table>

detection of phytophthora capsici in irrigation water using loop-mediated isothermal amplification

Phytophthora capsici is a devastating oomycete pathogen that affects many important solanaceous and cucurbit crops causing significant economic losses in vegetable production annually. Phytophthora capsici is soil-borne and a persistent problem in vegetable fields due to its long-lived survival structures (oospores and chlamydospores) that resist weathering and degradation. The main method of dispersal is through the production of zoospores, which are single-celled, flagellated spores that can swim through thin films of water present on surfaces or in water-filled soil pores and can accumulate in puddles and ponds. Therefore, irrigation ponds can be a source of the pathogen and initial points of disease outbreaks. Detection of P. capsici in irrigation water is difficult using traditional culture-based methods because other microorganisms present in the environment, such as Pythium spp., usually overgrow P. capsici making it undetectable. To determine the presence of P. capsici spores in water sources (irrigation water, runoff, etc.), we developed a hand pump-based filter paper (8-10 &#181;m) method that captures the pathogen&#8217;s spores (zoospores) and is later used to amplify the pathogen&#8217;s DNA through a novel loop-mediated isothermal amplification (LAMP) assay designed for the specific amplification of P. capsici. This method can amplify and detect DNA from a concentration as low as 1.2 x 102 zoospores/mL, which is 40 times more sensitive than conventional PCR. No cross-amplification was obtained when testing closely related species. LAMP was also performed using a colorimetric LAMP master mix dye, displaying results that could be read with the naked eye for on-site rapid detection. This protocol could be adapted to other pathogens that reside, accumulate, or are dispersed via contaminated irrigation systems.

Optimization of LAMP method 
In this study, we detected the presence of Phytophthora capsici in irrigation water using a portable loop-mediated isothermal amplification (LAMP) assay. First, the proposed LAMP assay was optimized by testing different LAMP primer concentrations [F3, B3 (0.1&#8211;0.5 &#181;M each); LF, LB (0.5&#8211;1.0 &#181;M each) and FIP, BIP (0.8&#8211;2.4 &#181;M each)], durations (30&#8211;70 min), and temperatures (55&#8211;70 &#176;C). The final LAMP primer mix used i...

Watch this Scientific Journal Video about Detection of Phytophthora capsici in Irrigation Water using Loop-Mediated Isothermal Amplification at JoVE.com

Detection of Phytophthora capsici in Irrigation Water using Loop-Mediated Isothermal Amplification

We developed a method to detect Phytophthora capsici zoospores in water sources using a filter paper DNA extraction method coupled with a loop-mediated isothermal amplification (LAMP) assay that can be analyzed in the field or in the lab.

Detection of Phytophthora capsici in Irrigation Water using Loop-Mediated Isothermal Amplification

Phytophthora capsici is a devastating oomycete pathogen that affects many important solanaceous and cucurbit crops causing significant economic losses in ...

Phytopathogen detection is a crucial step in plant disease management. This protocol provides a rapid detection method for irrigation water contamination due to a common waterborne fighter pathogen. Using this technique, specific pathogen, such as Phytophthora capcici, can be processed and rapidly detected from our large volume of irrigation water while remaining on site.Demonstrating the procedure will be Owen Hudson, a Masters student from my laboratory, and Sumyya Waliullah, a PostDoctoral researcher from Dr.Pingxi G's laboratory to set up a pump and filter for on site Phytophthora capcici detection in irrigation water. Attach a filtering flask to a tube connected to a hand pump and fitted buchner funnel into the rubber stopper in the mouth of the filtering flask. Then fit an appropriately sized piece of filter paper with a 15 micron retention size into the funnel.To obtain water samples collect irrigation water from the targeted source. The water may have small amounts of debris, but not significant sediment or soil. Slowly pour between 50 to 1000 milliliters of test water over the filter paper inside the funnel while using the hand pump to create a suction to pull the water through the funnel.When all of the water has been filtered, use forceps to remove the filter paper from the funnel. And use sterile scissors to cut the paper into small pieces. Submerge eight to 12 pieces of paper in 400 microliters of extraction buffer in a 1.5 milliliter tube for a five minute incubation at room temperature.Vortex or otherwise agitate the paper for 10 seconds once every minute. At the end of the incubation, use forceps to remove the paper with as little buffer as possible. And repeat the license with the next set of filter paper pieces.For DNA extraction from the filter paper samples added 20 microliters of proteinase K and 10 microliters of 10 nanograms per microliter RNAs to the sample too and incubate the solution at room temperature for 15 minutes with vortexing or shaking every three minutes. At the end of the incubation, add 500 microliters of magnetic beads in binding buffer to the sample and mix well by shaking. After five minutes at room temperature, place the tube and the magnetic separator rack for two minutes before removing and discarding the supernatant.Remove the tube from the magnetic separator and vigorously re-suspend the beads in 500 microliters of wash buffer. After 30 seconds return the tube to the magnet and wait two minutes before discarding the supernatant. Repeat the wash with 500 microliters of wash buffer too and 500 microliters of 80%ethanol as just demonstrated.And air drive the magnetic bead pellet for 15 minutes at room temperature. At the end of the incubation re-suspend the beads in 50 microliters of elution buffer with pipetting for one minute before placing the tube back onto the magnet for two minutes to allow collection of the supernatant. After preparing the LAMP primer mix as indicated in the table, add at 2.5 microliters of primer mix 12.5 microliters of a lava LAMP mastermix one microliter of extracted DNA and nine microliters of double distilled water to a PCR tube and set up one positive and one negative control.incubate all of the samples in a 64 degrees Celsius heat blog for 45 minutes or the genie three amplification instrument at the end of the incubation, a load of five microliters of each amplified sample onto a 1%agarose gel and image the resulting bands on an ultraviolet imaging machine. If a calorimetric dye was used, view the color change to determine the results as positive or negative. If a portable amplification instrument was used, view the amplification graph on the screen to determine the results.The optical time for running the LAMP assay at 64 degrees is 45 minutes, as the lowest concentrations that were positive for detection are not amplified until 40 minutes, while higher concentrations are amplified at 20 minutes. Amplification can be confirmed on a 1%agarose gel labeled with a Nucleic acid stain. As illustrated conventional PCR is 40 times less sensitive than LAMP.Detecting 4.8 times 10 to the third zoospores per milliliter concentrations at the lowest. In this analysis, water samples were collected from seven ponds used for commercial vegetable production in Tift County, Georgia. Three of which demonstrated positive LAMP results.When the samples were tested by conventional PCR however, zoospores were detected in only one of the three positive samples. In this table, the differences between detection methods using such variables as sensitivity, time, required preparation, materials and cost are summarized. LAMP is the least expensive method among the tested methods, and is also the fastest, requiring only 30 to 60 minutes for amplification compared to conventional PCR amplification.Using this protocol DNA extracted from closely related UMI seed pathogens results in no detection for any of the samples, confirming the specificity of the primers. Make sure not to pour the sample water too fast and be careful when adding extracted DNA to the LAMP tubes to limit contamination. Once other waterborne pathogens have had their specific primer sets developed, the filtration and lamp acid methods can be adapted for other pathogens.

detection-phytophthora-capsici-irrigation-water-using-loop-mediated

Research

JoVE Journal

Environment

Colorimetric Paper-based Detection of Escherichia coli, Salmonella spp., and Listeria monocytogenes from Large Volumes of Agricultural Water

This protocol describes rapid colorimetric detection of Escherichia coli, Salmonella spp., and Listeria monocytogenes from large volumes (10 L) of agricultural waters. Here, water is filtered through sterile Modified Moore Swabs (MMS), which consist&#160;of a simple gauze filter enclosed in a plastic cartridge, to concentrate bacteria. Following filtration, non-selective or selective enrichments for the target bacteria are performed in the MMS. For colorimetric detection of the target bacteria, the enrichments are then assayed using paper-based analytical devices (&#181;PADs) embedded with bacteria-indicative substrates. Each substrate reacts with target-indicative bacterial enzymes, generating colored products that can be detected visually (qualitative detection) on the &#181;PAD. Alternatively, digital images of the reacted &#181;PADs can be generated with common scanning or photographic devices and analyzed using ImageJ software, allowing for more objective and standardized interpretation of results. Although the biochemical screening procedures are designed to identify the aforementioned bacterial pathogens, in some cases enzymes produced by background microbiota or the degradation of the colorimetric substrates may produce a false positive. Therefore, confirmation using a more discriminatory diagnostic is needed. Nonetheless, this bacterial concentration and detection platform is inexpensive, sensitive (0.1 CFU/ml detection limit), easy to perform, and rapid (concentration, enrichment, and detection are performed within approximately 24&#160;hr), justifying its use as an initial screening method for the microbiological quality of agricultural water.

Colorimetric Paper-based Detection of Escherichia coli, Salmonella spp., and Listeria monocytogenes from Large Volumes of Agricultural Water

A protocol involving integrated concentration, enrichment, and end-point colorimetric detection of foodborne pathogens in large volumes of agricultural water is presented here. Water is filtered through Modified Moore Swabs (MMS), enriched with selective or non-selective media, and detection is performed using paper-based analytical devices (&#181;PAD) imbedded with bacterial-indicative colorimetric substrates.

This protocol describes rapid colorimetric detection of Escherichia coli, Salmonella spp., and Listeria monocytogenes from large volumes (10 L) of ...

Laboratory-determined Phosphorus Flux from Lake Sediments as a Measure of Internal Phosphorus Loading

Eutrophication is a water quality issue in lakes worldwide, and there is a critical need to identify and control nutrient sources. Internal phosphorus (P) loading from lake sediments can account for a substantial portion of the total P load in eutrophic, and some mesotrophic, lakes. Laboratory determination of P release rates from sediment cores is one approach for determining the role of internal P loading and guiding management decisions. Two principal alternatives to experimental determination of sediment P release exist for estimating internal load: in situ measurements of changes in hypolimnetic P over time and P mass balance. The experimental approach using laboratory-based sediment incubations to quantify internal P load is a direct method, making it a valuable tool for lake management and restoration.
Laboratory incubations of sediment cores can help determine the relative importance of internal vs. external P loads, as well as be used to answer a variety of lake management and research questions. We illustrate the use of sediment core incubations to assess the effectiveness of an aluminum sulfate (alum) treatment for reducing sediment P release. Other research questions that can be investigated using this approach include the effects of sediment resuspension and bioturbation on P release.
The approach also has limitations. Assumptions must be made with respect to: extrapolating results from sediment cores to the entire lake; deciding over what time periods to measure nutrient release; and addressing possible core tube artifacts. A comprehensive dissolved oxygen monitoring strategy to assess temporal and spatial redox status in the lake provides greater confidence in annual P loads estimated from sediment core incubations.

Lake eutrophication is a water quality issue worldwide, making the need to identify and control nutrient sources critical. Laboratory determination of phosphorus release rates from sediment cores is a valuable approach for determining the role of internal phosphorus loading and guiding management decisions.

Eutrophication is a water quality issue in lakes worldwide, and there is a critical need to identify and control nutrient sources. Internal phosphorus (P) ...

EPA Method 1615. Measurement of Enterovirus and Norovirus Occurrence in Water by Culture and RT-qPCR. I. Collection of Virus Samples

EPA Method 1615 was developed with a goal of providing a standard method for measuring enteroviruses and noroviruses in environmental and drinking waters. The standardized sampling component of the method concentrates viruses that may be present in water by passage of a minimum specified volume of water through an electropositive cartridge filter. The minimum specified volumes for surface and finished/ground water are 300 L and 1,500 L, respectively. A major method limitation is the tendency for the filters to clog before meeting the sample volume requirement. Studies using two different, but equivalent, cartridge filter options showed that filter clogging was a problem with 10% of the samples with one of the filter types compared to 6% with the other filter type. Clogging tends to increase with turbidity, but cannot be predicted based on turbidity measurements only. From a cost standpoint one of the filter options is preferable over the other, but the water quality and experience with the water system to be sampled should be taken into consideration in making filter selections.

EPA Method 1615 uses an electropositive filter to concentrate enteroviruses and noroviruses in environmental and drinking waters. This manuscript describes the procedure for collecting samples for Method 1615 analyses.

EPA Method 1615 was developed with a goal of providing a standard method for measuring enteroviruses and noroviruses in environmental and drinking waters. ...

A Small Volume Bioassay to Assess Bacterial/Phytoplankton Co-culture Using WATER-Pulse-Amplitude-Modulated (WATER-PAM) Fluorometry

Conventional methods for experimental manipulation of microalgae have employed large volumes of culture (20 ml to 5 L), so that the culture can be subsampled throughout the experiment1&#8211;7. Subsampling of large volumes can be problematic for several reasons: 1) it causes variation in the total volume and the surface area:volume ratio of the culture during the experiment; 2) pseudo-replication (i.e., replicate samples from the same treatment flask8) is often employed rather than true replicates (i.e., sampling from replicate treatments); 3) the duration of the experiment is limited by the total volume; and 4) axenic cultures or the usual bacterial microbiota are difficult to maintain during long-term experiments as contamination commonly occurs during subsampling.
The use of microtiter plates enables 1 ml culture volumes to be used for each replicate, with up to 48 separate treatments within a 12.65 x 8.5 x 2.2 cm plate, thereby decreasing the experimental volume and allowing for extensive replication without subsampling any treatment. Additionally, this technique can be modified to fit a variety of experimental formats including: bacterial-algal co-cultures, algal physiology tests, and toxin screening9&#8211;11. Individual wells with an alga, bacterium and/or co-cultures can be sampled for numerous laboratory procedures including, but not limited to: WATER-Pulse-Amplitude-Modulated (WATER-PAM) fluorometry, microscopy, bacterial colony forming unit (cfu) counts and flow cytometry. The combination of the microtiter plate format and WATER-PAM fluorometry allows for multiple rapid measurements of photochemical yield and other photochemical parameters with low variability between samples, high reproducibility and avoids the many pitfalls of subsampling a carboy or conical flask over the course of an experiment.

A Small Volume Bioassay to Assess Bacterial/Phytoplankton Co-culture Using WATER-Pulse-Amplitude-Modulated WATER-PAM Fluorometry

The goal of this procedure is to demonstrate the reproducibility and adaptability of using a microtiter plate format for microalgal screening. This rapid screen combines WATER-Pulse-Amplitude-Modulated (WATER-PAM) fluorometry to measure photosynthetic yield as an indicator of Photosystem II (PSII) health with small volume bacterial-algal co-cultures.

Conventional methods for experimental manipulation of microalgae have employed large volumes of culture (20 ml to 5 L), so that the culture can be ...

EPA Method 1615. Measurement of Enterovirus and Norovirus Occurrence in Water by Culture and RT-qPCR. Part III. Virus Detection by RT-qPCR

EPA Method 1615 measures enteroviruses and noroviruses present in environmental and drinking waters. This method was developed with the goal of having a standardized method for use in multiple analytical laboratories during monitoring period 3 of the Unregulated Contaminant Monitoring Rule. Herein we present the protocol for extraction of viral ribonucleic acid (RNA) from water sample concentrates and for quantitatively measuring enterovirus and norovirus concentrations using reverse transcription-quantitative PCR (RT-qPCR). Virus concentrations for the molecular assay are calculated in terms of genomic copies of viral RNA per liter based upon a standard curve. The method uses a number of quality controls to increase data quality and to reduce interlaboratory and intralaboratory variation. The method has been evaluated by examining virus recovery from ground and reagent grade waters seeded with poliovirus type 3 and murine norovirus as a surrogate for human noroviruses. Mean poliovirus recoveries were 20% in groundwaters and 44% in reagent grade water. Mean murine norovirus recoveries with the RT-qPCR assay were 30% in groundwaters and 4% in reagent grade water.

Here we present a procedure to quantify enterovirus and norovirus in environmental and drinking waters using reverse transcription-quantitative PCR. Mean virus recovery from groundwater with this standardized procedure from EPA Method 1615 was 20% for poliovirus and 30% for murine norovirus.

EPA Method 1615 measures enteroviruses and noroviruses present in environmental and drinking waters. This method was developed with the goal of having a ...

Screening for Endocrine Activity in Water Using Commercially-available In Vitro Transactivation Bioassays

In vitro transactivation bioassays have shown promise as water quality monitoring tools, however their adoption and widespread application has been hindered partly due to a lack of standardized methods and availability of robust, user-friendly technology. In this study, commercially available, division-arrested cell lines were employed to quantitatively screen for endocrine activity of chemicals present in water samples of interest to environmental quality professionals. A single, standardized protocol that included comprehensive quality assurance/quality control (QA/QC) checks was developed for Estrogen and Glucocorticoid Receptor activity (ER and GR, respectively) using a cell-based Fluorescence Resonance Energy Transfer (FRET) assay. Samples of treated municipal wastewater effluent and surface water from freshwater systems in California (USA), were extracted using solid phase extraction and analyzed for endocrine activity using the standardized protocol. Background and dose-response for endpoint-specific reference chemicals met QA/QC guidelines deemed necessary for reliable measurement. The bioassay screening response for surface water samples was largely not detectable. In contrast, effluent samples from secondary treatment plants had the highest measurable activity, with estimated bioassay equivalent concentrations (BEQs) up to 392 ng dexamethasone/L for GR and 17 ng 17&#946;-estradiol/L for ER. The bioassay response for a tertiary effluent sample was lower than that measured for secondary effluents, indicating a lower residual of endocrine active chemicals after advanced treatment. This protocol showed that in vitro transactivation bioassays that utilize commercially available, division-arrested cell &#34;kits&#34;, can be adapted to screen for endocrine activity in water.

Screening for Endocrine Activity in Water Using Commercially-available In Vitro Transactivation Bioassays

A protocol to screen for endocrine activity in organic extracts of water samples, including treated wastewater effluent and surface (receiving) water, was adapted using commercially available division-arrested ("freeze and thaw") in vitro transactivation bioassays.

In vitro transactivation bioassays have shown promise as water quality monitoring tools, however their adoption and widespread application has been ...

A Simple Planting Technique for Re-establishing Trees Where Frequent Inundation Occurs

Many of the Everglades tree islands have lost elevation over the past century and most of their trees have died such that they are now covered with herbaceous plants. This protocol describes a simple, cost-effective tree planting technique needed for restoring degraded Everglade tree islands. The design is patterned after a natural Everglades process that creates floating peat islands, which allows tree survival and growth in flooded conditions and often leads to the development of tree islands. Commercially available peat bags were used as the medium for the growth and establishment of potted native tree saplings. The pop-up configuration floated initially and provided additional elevation to minimize inundation, with a single native tree species sapling and a single tree fertilizer spike. During a 3 year study involving 105 pop-ups, most plants survived (80%) and many thrived. Determining whether this technique can establish trees on a degraded tree island will require longer studies and extensive field tests.

This protocol describes a simple, cost-effective tree planting technique for restoring degraded Everglades tree islands that experience inundation. The design creates an island (pop-up) which floats initially and adds elevation to promote tree survival and growth under flooded conditions.

Many of the Everglades tree islands have lost elevation over the past century and most of their trees have died such that they are now covered with ...

Bioindication Testing of Stream Environment Suitability for Young Freshwater Pearl Mussels Using In Situ Exposure Methods

Knowledge of habitat suitability for freshwater mussels is an important step in the conservation of this endangered species group. We describe a protocol for performing in situ juvenile exposure tests within oligotrophic river catchments over one-month and three-month periods. Two methods (in both modifications) are presented to evaluate the juvenile growth and survival rate. The methods and modifications differ in value for the locality bioindication and each has its benefits as well as limitations. The sandy cage method works with a large set of individuals, but only some of the individuals are measured and the results are evaluated in bulk. In the mesh cage method, the individuals are kept and measured separately, but a low individual number is evaluated. The open water exposure modification is relatively easy to apply; it shows the juvenile growth potential of sites and can also be effective for water toxicity testing. The within-bed exposure modification needs a high workload but is closer to the conditions of a natural juvenile environment and it is better for reporting the real suitability of localities. On the other hand, more replications are needed in this modification due to its high-hyporheic environment variability.

Bioindication Testing of Stream Environment Suitability for Young Freshwater Pearl Mussels Using In Situ Exposure Methods

In situ bioindications enable determination of the suitability of an environment for endangered mussel species. We describe two methods based on the juvenile exposure of freshwater pearl mussels in cages to oligotrophic river habitats. Both methods are implemented in variants for open water and hyporheic water environments.

Knowledge of habitat suitability for freshwater mussels is an important step in the conservation of this endangered species group. We describe a protocol ...

Optimized Procedure for Determining the Adsorption of Phosphonates onto Granular Ferric Hydroxide using a Miniaturized Phosphorus Determination Method

This paper introduces a procedure to investigate the adsorption of phosphonates onto iron-containing filter materials, particularly granular ferric hydroxide (GFH), with little effort and high reliability. The phosphonate, e.g., nitrilotrimethylphosphonic acid (NTMP), is brought into contact with the GFH in a rotator in a solution buffered by an organic acid (e.g., acetic acid) or Good buffer (e.g., 2-(N-morpholino)ethanesulfonic acid) [MES] and N-cyclohexyl-2-hydroxyl-3-aminopropanesulfonic acid [CAPSO]) in a concentration of 10 mM for a specific time in 50 mL centrifuge tubes. Subsequently, after membrane filtration (0.45 &#181;m pore size), the total phosphorus (total P) concentration is measured using a specifically developed determination method (ISOmini). This method is a modification and simplification of the ISO 6878 method: a 4 mL sample is mixed with H2SO4 and K2S2O8 in a screw cap vial, heated to 148-150 &#176;C for 1 h and then mixed with NaOH, ascorbic acid and acidified molybdate with antimony(III) (final volume of 10 mL) to produce a blue complex. The color intensity, which is linearly proportional to the phosphorus concentration, is measured spectrophotometrically (880 nm). It is demonstrated that the buffer concentration used has no significant effect on the adsorption of phosphonate between pH 4 and 12. The buffers, therefore, do not compete with the phosphonate for adsorption sites. Furthermore, the relatively high concentration of the buffer requires a higher dosage concentration of oxidizing agent (K2S2O8) for digestion than that specified in ISO 6878, which, together with the NaOH dosage, is matched to each buffer. Despite the simplification, the ISOmini method does not lose any of its accuracy compared to the standardized method.

This paper introduces a procedure to investigate the adsorption of phosphonates onto iron-containing filter materials, particularly granular ferric hydroxide, with little effort and high reliability. In a buffered solution, the phosphonate is brought into contact with the adsorbent using a rotator and then analyzed via a miniaturized phosphorus determination method.

This paper introduces a procedure to investigate the adsorption of phosphonates onto iron-containing filter materials, particularly granular ferric ...

Construction of a Low-cost Mobile Incubator for Field and Laboratory Use

Incubators are essential for a range of culture-based microbial methods, such as membrane filtration followed by cultivation for assessing drinking water quality. However, commercially available incubators are often costly, difficult to transport, not flexible in terms of volume, and/or poorly adapted to local field conditions where access to electricity is unreliable. The purpose of this study was to develop an adaptable, low-cost and transportable incubator that can be constructed using readily available components. The electronic core of the incubator was first developed. These components were then tested under a range of ambient temperature conditions (3.5 &#176;C - 39 &#176;C) using three types of incubator shells (polystyrene foam box, hard cooler box, and cardboard box covered with a survival blanket). The electronic core showed comparable performance to a standard laboratory incubator in terms of the time required to reach the set temperature, inner temperature stability and spatial dispersion, power consumption, and microbial growth. The incubator set-ups were also effective at moderate and low ambient temperatures (between 3.5 &#176;C and 27 &#176;C), and at high temperatures (39 &#176;C) when the incubator set temperature was higher. This incubator prototype is low-cost (&lt; 300 USD) and adaptable to a variety of materials and volumes. Its demountable structure makes it easy to transport. It can be used in both established laboratories with grid power or in remote settings powered by solar energy or a car battery. It is particularly useful as an equipment option for field laboratories in areas with limited access to resources for water quality monitoring.

This paper describes a method for building an adaptable, low-cost and transportable incubator for microbial testing of drinking water. Our design is based on widely available materials and can operate under a range of field conditions, while still offering the advantages of higher-end laboratory-based models.

Incubators are essential for a range of culture-based microbial methods, such as membrane filtration followed by cultivation for assessing drinking water ...