The whitefly has acquired a gene from plants that makes plant antibodies harmless. This was reported by a team led by Youjun Zhang of the Chinese Academy of Agricultural Sciences in Beijing In the magazine “Cell”. This is the first time ever that a case has been discovered in which an insect takes genes from a plant.
The insect’s scientific name is tobacco or whitefly Bemisia tabaci. It is one of the most economically important pests in the world. The animals suck the sap, leaving behind sticky honey in which the fungi settle. It also transmits disease-causing viruses. Plants have little to stand up to this attack, because the scale insect is immune to at least one class of defense material, phenol glycosides, thanks to the inherited gene. Provides building instructions for an enzyme that neutralizes glycosides. It originally probably came from the same cellular mechanism by which plants still produce glycosides today. It likely reached the range of insect DNA several million years ago, possibly via a virus.
This special ability can now turn into the whitefly’s weakness. The pest, which has already become resistant to a number of insecticides, can be controlled precisely with the help of active ingredients that stop the action of the enzyme. Zhang team has already shown this in a trial. The test tomato was genetically modified in a way that produces a genetic switch for the enzyme with the help of RNA interference. Suddenly the scale insects fed from these tomatoes were no longer immune to glycosides and died. This opens up opportunities for a very specific control factor, says Joshua Gershenson of the Max Planck Institute for Chemical Ecology in Jena, who was not involved in the study. “You can keep whiteflies away, but at the same time avoid beneficial insects like pollinators,” He says in the science magazine “Nature”..
The fact that genes are passed from one organism to another is a common phenomenon in simple organisms such as protozoans or fungi, but also in plants themselves. However, if until now genes of strange origin have been found in insects, then they come exclusively from microorganisms. The fact that the enzyme that Zhang and colleagues discovered now comes from plants is a result of its genetic similarity to enzymes that have the same function in the plant kingdom.
Not all species known as whitefly carry it: greenhouse whiteflies should do without it. However, the team wrote that it might be helpful to look for other inherited genes in other insects. Thanks to the ever-expanding genetic databases, this should become easier in the future. Some of these genes could then also prove to be very promising targets for controlling targeted pests via RNA interference.
Update, March 29, 2021: The current study apparently, contrary to what the authors suggest, is not the first to discover indications of horizontal gene transfer in the scallop of the tobacco moth. In 2020, scientists working with Maximiliano Jauri from the Argentine University Nacional de San Luis published one a studyThey demonstrated that mosquitoes and scale insects took over genes from plants.