The magical “plant band-aid”

  Intractable “Huanglong Disease” The
  human world is struggling due to the new crown pneumonia. At the same time, there are several epidemic diseases that are endangering global crops, putting the production of citrus, olives and bananas at risk.
  For example, in Florida, the “sunshine state” in the United States, which accounts for 80% of the orange juice production in the United States, about half of the fruit trees in every citrus orchard are infected with a deadly epidemic from Asia called “Huanglong Disease” or ” Citrus Greening Disease”. After the disease, the roots of the fruit trees become deformed, the leaves are two centimeters shorter than normal, and they start to turn yellow. Fully grown citrus is still blue. They should be the size of a softball, but now they are only the size of a table tennis ball. The stunted fruit will fall and rot early, and then the entire tree will slowly die.
  The citrus groves in Florida are the most serious place of “Yellow Dragon Disease”. What’s more worrying is that the disease has spread to other parts of the world, including Mexico, India, Brazil and southern Africa, and infected a variety of crops, causing tens of billions of dollars in damage.
  Scientists have discovered through research that “Huanglong disease” is transmitted by an insect called “Asian citrus psyllid”, which carries pathogenic bacteria into plants and specifically infects the phloem in the plant’s circulatory system, especially the roots. Traditional treatment methods are difficult to reach these parts. Most pesticides are simply sprayed or smeared on the leaves or stems of plants, and it is difficult for antibacterial compounds to be transported to the roots of plants through the circulatory system.
  In order to fight against “Huanglong Disease” and save fruit trees, although scientists can cultivate several genetically modified plants to resist “Huanglong Disease”, this will allow fruit consumers to stay away. In contrast, improving the use of pesticides may be a better way. So Yunteng Cao, a Chinese biomedical doctor who was studying at the Massachusetts Institute of Technology, thought of a good way to put “band-aids” on plants.
  so-called “plant band-aid” is actually a microneedle patch.
  In human medicine, microneedle patches have been widely used. It usually contains a small square chip on which is covered with densely packed, small sharp micro-needles. These needles are made of silk materials such as keratin and silk protein and contain drugs. When the microneedle patch is attached to the body, it will pierce the surface of the skin painlessly. Then, the needle slowly dissolves, and gradually releases the drug into the interstitial fluid between skin cells, which then allows it to enter the blood. Compared with traditional injections, the microneedle patch is much less painful, has less risk of infection or other harm to the patient, and can continuously release the drug to increase the efficacy, so it is very popular with patients.
  Considering the above-mentioned advantages of microneedle patches, Cao Yunteng invented a plant microneedle patch that can be attached to the stems, leaves, roots or other parts of large plants to send pesticides, pesticides and other substances directly into their circulation In the system, the absorption efficiency is improved. Although plant microneedles are also made of silk materials, they are not the same as those used by humans. This is because the water in plants is usually less than that in humans, so microneedles need some help when dissolving. For this reason, the finished plant microneedles need to have strong hydrophilicity (water absorption) in order to make better use of water. But at the same time, plant microneedles still need to be tough enough to pierce the epidermis of plants. Like the human microneedle patch, compared to the traditional subcutaneous injection of plants, the use of plant microneedles does not cause so much damage to plants.
  In experiments, plant microneedles have been successfully used to inject fluorescent particles into tobacco plants and tomatoes, and then the fluorescent particles can be seen moving from the stems of the plants to the leaves and roots. In addition to transporting antibiotics or nutrients, plant microneedles have been shown to have many uses. It can help scientists understand transport phenomena in plants, and can also be used to transport genes to transform plants.
  So far, plant microneedle is a laboratory technology with precision equipment, and Cao Yunteng hopes that it will be used on a large scale in agriculture to combat “Huanglong Disease.” Therefore, his research team used a toy gun mounted on a small drone to test field applications. The toy gun can shoot plant microneedles into field plants. If the experiment results are good, then in the future, plant microneedles will be used in large-scale agricultural automated production.