Stolen plant gene shields insect from plant toxins

Usually, new genes arise in animals because of mutations, but occasionally they are ‘stolen’ from another organism.

A new paper, published in Cell, shows that the whitefly, an aphid-like insect, has stolen a plant gene. The addition to its genome may help it defensively breakdown plant toxins, which makes it an agricultural pest.

A team, led by Youjun Zhang from the the Chinese Academy of Agricultural Sciences, found that the whitefly had a plant gene called BtPMaT1 that it picked up from plants around 35 million years ago via horizontal gene transfer – where a gene crosses from one organism to another.

The gene may help store the toxins inside the insects’ cells in a harmless form, instead of letting the toxins poison the whitefly.

Key Research Points

  • The whitefly has an ancient plant gene
  • The gene was likely ‘stolen’ 35 million years ago via horizontal transfer
  • It helps protect the whitefly from plant toxins
  • GM tomatoes overcome this to kill whitefly pests

“This seems to be the first recorded example of the horizontal gene transfer of a functional gene from a plant into an insect,” says co-author Ted Turlings from the University of Neuchâtel, Switzerland.

“You cannot find this gene, BtPMaT1, which neutralizes toxic compounds produced by the plant, in any other insect species.”

Horizontal gene transfer happens to bacteria somewhat frequently, but it usually needs help from something else to happen in multi-cellular organisms. In this case, it is likely to have entered the whitefly genome because of a virus.

“We think a virus within the plant may have taken up this BtPMaT1 gene and, after ingestion by a whitefly, the virus then must have done something inside the insect whereby that gene was integrated into the whiteflies genome,” says Turlings.

“Of course, this is an extremely unlikely event, but if you think about millions of years and billions of individual insects, viruses, and plants across time, once in a while this could happen, and if the acquired gene is a benefit to the insects, then it will be evolutionarily favoured and may spread.”

 Using this knowledge, the team developed an RNA to prevent the gene from helping the whitefly defend itself, to act as a pesticide that doesn’t harm the plants.

“The most exciting step of this design was when our colleagues genetically manipulated tomato plants to start producing this RNA molecule” says Turlings.

“Once the whiteflies fed on the tomatoes and ingested the plant-produced RNA, their BtPMaT1 gene was silenced, causing 100% mortality of the insect, but the genetic manipulation had no impact on the survival of other insects that were tested.”

More on horizontal gene transfer

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