A University of Sussex mathematician, Dr. Konstantin Blyuss, working with biologists at the National Academy of Sciences of Ukraine, has developed a chemical-free way to precisely target a parasitic worm that destroys wheat crops.
The team has developed a method to 'silence' the harmful nematode's genes by using biostimulants derived from naturally occurring soil bacteria. The biostimulants also 'switch off' the plant's own genes that are affected by the nematodes, making it much harder for the parasite to harm the crop.
The gene silencing process is triggered when biostimulants, which are metabolites of bacteria occurring naturally in the soil, are applied to wheat. The biostimulants can be applied either by soaking the seeds or roots in a solution containing the biostimulants, or by adding the solution to the soil in which the plants are growing.
Dr. Blyuss said: "By soaking the seeds of the plant in the solution of biostimulants, the plant becomes a 'Trojan horse' for delivering special compounds produced inside the plants to the nematodes, which then kills them. We've targeted the specific genes of the nematode, so we know this won't affect other creatures."
The biostimulants only affect specific nematode and plant genes, and do not harm other species of insects. And because they are naturally occurring, rather than made of chemicals, they could potentially be used by organic farmers to make organic food more affordable in future.
Dr. Blyuss' mathematical modelling explains how RNA interference works in plants and shows the most effective way to apply the biostimulants to keep the crop safe from the harmful nematodes.
The team's experiments show that soaking the seeds of the plants in the biostimulant solution increases the chances of the plants surviving by between 57 to 92%. The technique also reduces the level of nematode infestation by 73 to 83% compared to plants grown without biostimulants.
Explaining the research, Dr. Blyuss said: "By using mathematical models, we learned how biostimulants are absorbed by wheat plants, so we now know the best way to deliver them. We've also looked at how the RNAi develops inside the plants and nematodes, how the plant is able to switch off specific genes involved in the process of nematode parasitism, thus stopping infestation, and how parts of RNAi from plants, when ingested by nematodes, cause their death by silencing some of their essential genes.
"These insights were combined with advanced experimental work on developing new strains of soil bacteria and extracting their metabolites, as well as with state-of-the-art molecular genetics analyses, to develop a new generation of environmentally safe tools for control of wheat nematodes.
"Some people are wary of genetically modified plants, so it's important to be clear that that is not what this is. Biostimulants effectively act as an 'inoculation' against nematode infestation. They achieve their effect by mobilising plants' internal machinery to produce compounds that protect plants against nematodes, while simultaneously causing nematode death.