Engineers from Massachusetts Institute of Technology have developed a potential cure for an ongoing plant epidemic, using silk-based biomaterials.
The supply of oranges, olives, and bananas is under threat in many areas. An ongoing epidemic is affecting the plants’ circulatory systems that cannot be stopped by pesticides.
A new technique, using silk-based biomaterials developed by engineers at Massachusetts Institute of Technology (MIT), may help farmers deliver life-saving treatments to plants ravaged by such diseases.
Precision medicine for plants
The team from MIT were inspired by some of the principals involved in precision medicine for humans. The team then adapted them to develop plant-specific biomaterials and drug-delivery devices.
The new treatment method uses microneedles made of a silk-based biomaterial to deliver nutrients, drugs, or other molecules to specific parts of the plant. The microneedles can be made in a variety of sizes and shapes, and can deliver material specifically to a plant’s roots, stems, or leaves, or into its vascular tissue.
In lab tests, the team used tomato and tobacco plants, but researchers say that the system could be adapted to almost any crop. The microneedles can not only deliver targeted payloads of molecules into the plant, but they can also be used to take samples from the plants for lab analysis.
The microneedles designed for human use are intended to biodegrade naturally in the body’s moisture. Due to plants having far less available water, the material did not dissolve and was not useful for delivering the pesticide or other macromolecules into the phloem.
The researchers decided to use silk as the basis for the microneedle because of its strength, its inertness in plants, and its ability to degrade into tiny particles that do not risk clogging the plant’s internal vasculature systems.
The findings are described in the journal Advanced Science, in a paper by MIT professors Benedetto Marelli and Jing-Ke-Weng, graduate student Yunteng Cao, postdoc Eugene Lim at MIT, and postdoc Menglong Xu at the Whitehead Institute for Biomedical Research.
The motive behind the research
This research was conducted in response to a request from the US Department of Agriculture. The request called for ideas on how to address the citrus greening crisis, which is has the potential to cause the collapse of a $9bn industry.
The citrus greening disease is spread by an insect called the Asian citrus psyllid that carries a bacterium into the plant. The disease infects the phloem of the whole plant, including roots, which are very difficult to reach with any conventional treatment.
“We wanted to solve the technical problem of how you can have a precise access to the plant vasculature,” Cao said. “Needles are very large and very invasive, and that results in damaging the plant,” he says. To find a substitute, they built on previous work that had produced microneedles using silk-based material for injecting human vaccines.
“We think this is a new tool that can be used by plant biologists and bioengineers to better understand transport phenomena in plants,” Cao says. In addition, it can be used “to deliver payloads into plants, and this can solve several problems. For example, you can think about delivering micronutrients, or you can think about delivering genes, to change the gene expression of the plant or to basically engineer a plant.”
The team continues to work on adapting the system to the varied needs and conditions of different kinds of plants and their tissues. “There’s a lot of variation among them, really,” Marelli says, “so you need to think about having devices that are plant-specific. For the future, our research interests will go beyond antibiotic delivery to genetic engineering and point-of-care diagnostics based on metabolite sampling.”
