Cape St Paul wilt disease (CSPWD) is a lethal disease of coconut palms caused by a phytoplasma, which is causing devastation throughout the coastal regions of Ghana. It is related to similar lethal diseases of coconut that are destroying coconut plantations in Tanzania, Mozambique, Mexico and parts of the Caribbean. Having developed a LAMP assay for diagnosis of this disease, we took the new Genie® II machine out to Sekondi/Takoradi in the Western Region of Ghana in April 2011 to begin field trialing of this rapid diagnostic system.
Samples were collected in the field by drilling into palm trunks and extracting approx 0.5g trunk borings into 5 mls alkaline polyethylene glycol DNA extraction buffer in plastic bottles containing 3 steel ball-bearings. The bottles were shaken for 2 mins to extract the DNA. Because the Genie® II we had taken out to Ghana was lacking the rechargeable battery at the time, samples were then taken back to the lab for the LAMP analysis, and 1 μl of the extracted DNA mix was added directly into 24 μl of the isothermal LAMP mix, which had been prepared 1 week earlier in Nottingham and shipped out to Ghana.
Positive amplification was detected in under 15 minutes from samples extracted from palms showing diseased symptoms, whilst no product was detected from symptomless palms. Positive amplifications were confirmed by the melt analysis option in the Genie® II machine. Further trials are planned for early in 2012, in which the battery operated system will be used in remote field locations for point-of-care tests. We are confident that the stability of the pre-prepared isothermal mastermixes, combined with the rapid 10 min extraction system will enable us to obtain results within 30 minutes of sampling.
This work is being funded by a Royal Society / Leverhulme Trust Africa Award and is a collaboration between the University of Nottingham UK, the Food and Environment Research Agency UK, and the Oilpalm Research Institute in Ghana.
School of Biosciences, University of Nottingham, Sutton Bonington Campus, Loughborough, LE12 5RD, UK
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