Whiteflies appear to have taken the saying “you are what you eat” somewhat literally. New research suggests the tiny, herbivorous insects have incorporated dozens of genes from plants into their own genome.
This volume of genes jumping from plant to animal far exceeds what was previously known in insects, and may lead to new ways to control this major pest of fruit and vegetable crops.
When DNA is passed between separate branches on the tree of life, it is called horizontal gene transfer. It is mainly known to occur between different species of bacteria, or between bacteria and eukaryotic organisms – those with cells containing membrane-bound organelles, like animals, plants and fungi.
Advertisement
In March 2021, researchers the first known case of plant-to-animal horizontal gene transfer in silverleaf whiteflies (Bemisia tabaci). Sometime in their evolutionary history, the insects acquired a single gene from a plant they ate, which may help them to detoxify chemical defences produced by plants.
and , both at the University of Paris-Saclay in France, developed a program to detect virus genes embedded in the genomes of eukaryotes. It works by using databases to identify the species a gene comes from, revealing foreign genetic material mixed in with the host’s genes. After seeing the 2021 study on whitefly gene transfer, they wondered if they could use their program to find more plant genes in the whitefly genome.
They found 50 different plant genes that the whiteflies acquired in 24 independent transfer events. Based on what scientists know about the genes most closely related to the transferred versions, many have some role in the plant’s response to parasites and disease.
Many of the genes are transcribed into RNA in the whiteflies’ cells, which suggests they have an active function, although the researchers haven’t tested their function directly.
Whiteflies are notorious agricultural pests that feed on hundreds of plant species. Maumus thinks the adopted genes may help the whiteflies adapt to a wide array of hosts.
It isn’t yet clear how these genes are taken up by the whiteflies, but viruses may play a role, says Maumus, given whiteflies are important carriers of scores of plant viruses. The genes may also piggyback on other jumping genetic elements called transposons.
The team’s analysis suggests that most of the genes transferred between 19 and 40 million years ago. “We don’t know actually if this [gene] vector is still alive today,” says Maumus.
“I’m quite amazed by the number of transfer events from plants to these insects,” says of Ghent University in Belgium, adding that it’s incredible that these genes have moved intact across kingdoms of life.
“The whole [genetic] machinery has to still maintain its function, and its interaction with other proteins also has to match,” he says. “That’s an additional layer of complexity.”
Wybouw’s own research has shown that microbial genes have moved into spider mite genomes, where they help to broaden the mites’ diet. “I think [horizontal gene transfer] is happening all the time [in eukaryotes],” he says. “And we have not been looking at it systematically enough.”
at the University of Neuchâtel in Switzerland – part of the team that reported the first plant-to-whitefly gene transfer – says the latest findings could lead to new ways of controlling the pests by interfering with the genes that let them cope with plant defences.
Reference: bioRxiv,
Sign up to Wild Wild Life, a free monthly newsletter celebrating the diversity and science of animals, plants and Earth’s other weird and wonderful inhabitants
