PRECISION INJECTION SYSTEM FOR PLANTS

While the human world is reeling from one pandemic, there are several ongoing epidemics that affect crops and put global food production at risk. Bananas, oranges are already under threat in many areas due to disease that affect plans circulatory system and that cannot be treated by applying pesticides.

A new method developed by engineers may offer a starting point for delivering life saving treatments to plants ravaged by diseases.

Diseases which are difficult to detect early and to treat, given the lack of precision tools to access plant vascularature to treat pathogens and to sample biomarkers. The team decided to take some of principles involved in precision medicine for humans and adapt them to develop plant-specific bio-materials and drug delivery devices.

This method uses an array of microneedles made of silk-based biomaterial to deliver nutrients, drugs or other molecules to specific parts of the plant.

One of the microneedle patches, applied to the citrus tree

The microneedles which is the researchers call phytoinjectors, 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 xylem (the vascular tissue involved in water transportation from roots to canopy) or phloem (the vascular tissue that circulates metabolites throughout the plant). In lab tests, the team used tomato and tobacco plants, but the system could be adopted 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 plans for lab analysis.

The work started in response for U.S.D.A to address the citrus greening crisis. The disease infects the phloem of the whole plant, including roots, which are very difficult to reach with any conventional treatment. Most pesticides are simply sprayed or painted onto a plant's leaves or stems, and little if any penetrates to the root system. Such treatments may appear to work for a short while, but then bacteria bounce back and do their damage. So, its needed something that can target the phloem circulating through a plant's tissues, which could carry an antibacterial compound down into the roots. Thats just what some version of the new microneedles could potentially accomplish.

Microneedle patch has been trailed on tomato plant

They used biotechnology tools to increase silk's hydrophilicity (making it attract water), while keeping the material strong enough to penetrate the plant's epidermis and degradable enough to then get out of the way.

They tested the material on their lab tomato and tobacco plants, and were able to observe injected materials, in this case fluorescent molecules, moving all the way through plant, from roots to leaves. In their experiment with tobacco plants, they were able to inject an organism called Agrobacterium to alter the plant's DNA- a typical bioengineering tool, but delivered in a new and precise way. The team continues to work on adapting the system to the varied needs and conditions of different kinds of plants and their tissues.

Source- Massachusetts institute of technology