By Bruce Barker
Call Susie Li a dreamer, but the researcher at Alberta Innovates Technology Futures at Vegreville, Alta., has developed a way for a tiny nano-biosensor to monitor sclerotinia spore levels in canola and alert a grower with a telephone call.
This may sound like science fiction, but Li has already proven that the concept works and is now verifying the technology in the greenhouse and canola fields, and moving the technology to a small device that can be easily applied in the field.
“The current method of forecasting for sclerotinia is with a checklist of questions in Saskatchewan and Alberta, and a risk assessment in Manitoba. But the checklists and risk assessments are not always reliable because of sudden weather changes,” Li says. “We wanted to develop a different way of predicting sclerotinia risk using technology that is available in other industries.”
Li’s solution is a combination of an in-field biosensor that can detect sclerotinia spores in real time that is linked to a signal transmission device that can call or text a cell phone. In order for the concept to work, the biosensor had to be able to specifically detect sclerotinia spores and correlate the number detected to the level that would cause the development of the disease.
“The biosensor technology is new but has been used in other areas. It was developed for applications in medicine, where it could detect DNA proteins and identify problems like diabetes,” Li says. The first part of the proof of concept was to be able to detect the spores through the development of an antibody specific to sclerotinia. An antibody recognizes the molecules used to produce a disease and blocks them in a way similar to antibodies used in influenza vaccinations. The antibody was placed on a nano-sensor and tested for sensitivity in the lab, where it detected sclerotinia spores down to levels as low as five spores.
“We thought this level was low enough for our design. The next thing we needed to know was how many spores are required to trigger a disease outbreak,” Li says.
In the greenhouse, various spore collection fluid samplers/traps were evaluated, and the Versa Trap from SKC Inc. was selected. Canola plants were grown in the growth chamber along with a jar of sand containing germinating sclerotia. Spores were collected in the trap and fluid transferred to the biosensor for spore detection. At the same time, the plants were monitored for the disease. Liquid samples from the spore trap were plated every 24 hours to identify disease development. Li was able to correlate that 10 sclerotia spores per millilitre collected in 24 hours in a 3.3-square-metre growth chamber started to cause leaf infection.
An additional step was to take the biosensor readings and convert them to an electronic signal transmission. Researchers at the University of Alberta accomplished this process using Bluetooth technology. The signal transmission process has already been established in the lab. When spores are detected, the level of spores detected influences the electrical conductivity on the biosensor. Higher conductivity results in a stronger signal sent over Bluetooth.
In 2016, Li started working on verifying the specificity and accuracy of the biosensor in the greenhouse and in canola fields over three years. She needs to know how big of an area one sensor can cover, the number required in a field, and how to make the technology work on an economic basis. “More work needs to be done to improve the sensitivity and lowering the detection limit. That is what we are working on right now,” Li says.