Researchers trial affordable rapid test to target “high impact” viruses in key food crops

Scientists from New Zealand’s Ministry for Primary Industries (MPI) are developing a low-cost diagnostic tool that could significantly boost staple crop production in developing countries.

The rapid test — the PlantdX2.0 tool — uses a combination of chemistries to spot plant disease. It will enable growers to weed out unhealthy plants in the field while it’s still early in the growing season. This can increase the production of key crops, which serve as crucial food sources worldwide.

“PlantdX2.0 will improve food security for maize and beans by eventually allowing farmers to use an inexpensive sensitive detection method for high impact viruses in these crops,” Dr. Jeremy Thompson, team manager, Virology and Phytoplasmology at the MPI’s Plant Health and Environment Laboratory (PHEL) tells Food Ingredients First.

“At the moment, the kit is being developed for a select number of relevant viruses to assess its robustness in the field. A crop-specific kit able to detect a range of viruses, such as maize and beans, is the long-term goal.”

Housed within PHEL, the scientists are collaborating with researchers from Northwestern University in Illinois (NU), US, to build the tool, which has shown encouraging results in the field, according to MPI.

Rapid testing for plant disease

Early prototypes of the test were used in New Zealand to catch virus infection in tomato plants that did not show any symptoms. More recently, the technology was trialed in Kenya’s Maseno area, where beans, sweet potato, and maize are staples in the diet.

Thompson shares that the tool has most effectively detected diseases such as cucumber mosaic virus (CMV), sweet potato feathery mottle virus, African cassava mosaic virus, and Pepino mosaic virus. CMV, for example, causes significant agronomic losses in many crops globally and likely has one of the broadest host ranges among plant viruses, according to research.

He notes that the technology can be adapted for high-value crops like fruits and vegetables, and it has potential applications in human and animal health.

“The test has been trialed on crude plant lysates from a range of different plant species without significant impact on sensitivity. The main challenge with fruits would be an adequate sampling of larger plants and trees that may have an uneven distribution of the pathogen. Initial experiments using PlantdX2.0 showed reliable virus detection when bulking up to 20 leaf samples.”

The “ultimate aim” is to create a test line read-out system, like the COVID-19 rapid antigen tests, that farmers can use midway through the two-year trial to identify and remove specific diseases.

Implications for developing countries

According to the research team, growers in developing countries grappling with low yields might unknowingly be breeding from diseased plants. Their access to conventional testing technology might also be strained.

Thompson says the project is developing a strip-based test that could be competitive with current plant disease detection apparatus in terms of cost and ease of use.

“A Lateral Flow Assay format is in progress but not yet optimized. Based on current calculations, the test should cost less than US$3, is more sensitive than existing serological kits, and works at 37°C, so minimal hardware is required.”

The project is funded by a US$1 million grant from the Bill and Melinda Gates Foundation and is led by Julius Lucks, professor of Chemical and Biological Engineering at NU.