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New technology to help farmers prevent bacterial wilt in potatoes

bacterial wilt LAMP

The International Potato Center (CIP) in collaboration with the Kenya Plant Health Inspectorate Service (KEPHIS) have validated a new technology to detect bacterial wilt in potatoes.

The cost-effective field deployable LAMP (Loop-mediated Isothermal Amplification) assay for the detection of bacteria that causes wilt from stem, leaf, tuber and soil will speed up the seed inspection and certification process.

Bacterial wilt is one of the most significant limitations to clean potato seed production, an essential component of high yields in many countries in Sub Saharan Africa. It has resulted in 30-100 per cent potato yield losses putting a huge dent on food security and livelihoods of many smallholder farmers.

With LAMP, it takes a shorter time to get the results (0.3 to 1 hour) as compared to the other methods that take two to 120 hours. Furthermore, the fact that it requires less expertise and its cost effectiveness means that medium to large scale producers can easily integrate LAMP Assay into self-assessment of their seed quality.

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Abdulwahab Abdurahman, a Molecular Biologist from CIP, taking trainees through different steps of LAMP assay in Ralstonia diagnosis from soil, stem and tuber samples, and showing trainees how to obtain readings from a tablet after tests using a Bio-Ranger and Gene II, and how to use the machine.

The current seed potato certification process in Kenya involves traditional laboratory processes such as ELISA (Enzyme-Linked Immunosorbent Assay) and PCR (Polymerase chain reaction) in the diagnosis of the bacterial wilt pathogen.

Field deployable LAMP assay has proved to be efficient and effective as it is sensitive, rapid, and accurate as compared to ELISA and PCR tests and does not require sending samples to the lab for analysis. The introduction of the field deployable LAMP assay has a significant advantage over the standard ELISA and PCR tests in its suitability for on-site diagnosis be it farmers field or point of entry.

In many countries, seed potato certification standards have zero tolerance for bacterial wilt pathogen and can lead to rejection of an entire potato field for seed. This therefore puts certified seed potato production that currently barely meets two per cent of the total area planted with potato at a high risk. There are a few seed merchants that produce certified seed potato and increasing quantities of certified seed is a major priority to improve yields and meet the increasing food demands.

To this end, through the support from GIZ-BMZ funded project on “Improved Diagnostics and genetic/molecular diversity of Ralstonia from Kenya and Uganda” CIP and KEPHIS conducted a two day training aimed at capacity building of East African countries’ seed regulatory and phytosanitary authorities as well as private diagnostic clinic personnel on the use of “field deployable LAMP assay to detect Ralstonia from stem, tuber and soil sample. The training was held at KEPHIS Plant Quarantine and Bio-safety 

The trainees got hands-on training on how to detect Ralstonia (bacteria) from stem, tuber and soil where they participated in extraction, preparation and testing samples using the LAMP assay. They were also taken through the assay validation process where they were shown sigmoid curves that show positive tests for Ralstonia. 

Trainees were impressed with the technology as it requires fewer reagents, simple laboratory skills and expertise, and helps in making informed and fast decisions on whether to accept or reject potato seed in the field. They also appreciated the use of the technique as it is specific and suggested adoption and use during inspections, surveillance and at border points. They added that, other protocols for diagnosis of various diseases in different plants should be developed.

Dr. Kalpana Sharma, Plant Pathologist from CIP is confident that faster decision-making arising from less than an hour of using the field-deployable LAMP assay versus 14 days of current practice by KEPHIS would not only help famers to go for seed or ware potato market but also encourage small and medium scale producers to become certified seed producers with greater certainty, thus promoting the seed sector investment and growth.

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