University researchers have discovered a faster way to collect DNA from plant tissue to test for disease, which often spreads rapidly across a garden or farm.
Conventional methods use bulky equipment to isolate and extract the molecular biomarker needed to identify disease, but the new technique extracts the DNA through a microneedle patch applied directly to the plant leaf.
“This discovery presents a very general protocol to isolate the DNA, and that's usually the first step of the molecular detection of disease,” says Qingshan Wei, an assistant professor at North Carolina State University and co-author of the study, Extraction of Plant DNA by Microneedle Patch for Rapid Detection of Plant Diseases.
Disease identification uses molecular diagnostics that can detect specific sequences in DNA that may be associated with disease. With the microneedle patch, the DNA can be collected in just one minute. Conventional tests, or assays, are usually done in a lab and require minimally three or four hours to complete.
“The current limitation is that the process to isolate molecule markers is very tedious because you have to use equipment to run the assays on,” says Wei. “We try to speed up the result turnaround time, so growers can get results faster.”
The microneedle patch, which is the size of a postage stamp, is made up of hundreds of tiny needles that collect genetic material. After applying the patch to a plant leaf for a few seconds, it is removed and rinsed with a buffer solution to wash off the material into a sterile container for testing.
The extraction technique has not been tested on ornamental plants and flowers, but the method has the potential to work on any type of leaf. Tomato and pepper plants were used in the initial study, but researchers were also able to use the microneedles patches to collect DNA from banana leaves, which have tougher tissue.
“Even with the differences in plant tissue, our technique should still be able to isolate the molecules,” says Wei. “We only tested it on a few plants in the study, but there is potential it could be applied to different types of plants.”
The researchers see this development as the first step towards creating an integrated system that allows a grower to collect and analyze DNA samples and receive immediate results from a mobile device. On-site testing technology could help growers quickly detect diseases to prevent widespread infection of their plants.
The paper was authored by Rajesh Paul, a Ph.D. student at NC State. Wei co-authored the paper along with several other researchers from NC State, UNC-CH, UCLA and Tianjin University. It was published in ACS Nano, an international journal of nanoscience and nanotechnology research.
The research was done with support from NC State Chancellor’s Faculty Excellence Program on Emerging Plant Disease and Global Food Security, the Kenan Institute for Engineering, Technology & Science at NC State, and the USDA Integrated Pest Information Platform for Extension and Education.
The abstract is available at https://pubs.acs.org/doi/10.1021/acsnano.9b00193.