Some whiteflies use plant genes to render toxins of their meals innocent.Credit: Getty
A pernicious agricultural pest owes a few of its success to a gene pilfered from its plant host hundreds of thousands of years in the past.
The discovering, reported at this time in Cell1, is the primary known instance of a pure gene transfer from a plant to an insect. It additionally explains one motive why the whitefly Bemisia tabaci is so adept at munching on crops: the gene that it swiped from vegetation allows it to neutralize a toxin that some vegetation produce to defend towards bugs.
Early work means that inhibiting this gene can render the whiteflies susceptible to the toxin, offering a possible route to combating the pest. “This exposes a mechanism through which we can tip the scales back in the plant’s favour,” says Andrew Gloss, who research plant–pest interactions on the University of Chicago in Illinois. “It’s a remarkable example of how studying evolution can inform new approaches for applications like crop protection.”
The diminutive whitefly — which is extra intently associated to aphids than to flies — wreaks agricultural havoc world wide. B. tabaci is among the many most harmful plant pests: whiteflies sup sugary sap from lots of of varieties of plant, all of the whereas excreting a sticky, candy substance referred to as honeydew that serves as a breeding floor for mould. Whiteflies are additionally vectors for greater than 100 pathogenic plant viruses.
Stolen genes
That some species of whitefly might owe a part of their predatory prowess to genes from different organisms isn’t totally stunning, as a result of genetic thievery is frequent within the arms race between vegetation and their pests. Over hundreds of thousands of years, vegetation and bugs alike have borrowed closely from microbial genomes, typically utilizing their newly acquired genes to develop defensive or offensive methods.
Some bugs, such because the espresso berry borer (Hypothenemus hampei), have plundered microbial genes to extract extra diet from hard-to-digest plant cell partitions2, and a wild relative of wheat has pilfered a fungal gene to struggle off a fungal illness referred to as head blight3. But vegetation and bugs weren’t known to steal from one another prior to now.
Entomologist Youjun Zhang on the Chinese Academy of Agricultural Sciences in Beijing and his colleagues had been scouring the B. tabaci genome for stolen genes, once they discovered one which appeared to have developed not in different bugs or microbes, however in vegetation.
Further examine confirmed that the gene can transfer a chemical group on to defensive compounds referred to as phenolic glucosides. Such compounds are made by many vegetation, together with tomatoes, to keep off pests. But the modification attributable to the whitefly gene rendered the compounds innocent.
To take a look at the speculation, the group engineered tomato vegetation to produce a double-stranded RNA molecule able to shutting down expression of the whitefly gene. Nearly the entire whiteflies that subsequently ate up these doctored tomato vegetation died.
That outcome suggests a brand new technique of concentrating on whiteflies, says Jonathan Gershenzon, a chemical ecologist on the Max Planck Institute for Chemical Ecology in Jena, Germany. “It offers an enormous chance to be specific,” he says. “You could keep the whiteflies away but not harm beneficial insects such as pollinators.”
Plants-pests battle
Gene transfer between species might be tough to show, says examine co-author Ted Turlings, a chemical ecologist on the University of Neuchâtel in Switzerland. To accomplish that, Zhang, Turlings and their colleagues analysed the sequences of comparable genes in vegetation, and decided that the whitefly gene was their evolutionary kin. The group additionally carried out analyses to present that the gene was built-in into the whitefly genome, and was not the results of plant DNA contaminating samples.
The outcomes had been stunning, however convincing, says Yannick Pauchet, a molecular entomologist additionally on the Max Planck Institute for Chemical Ecology. “According to the data they provide, horizontal gene transfer is the most parsimonious explanation,” he says.
But how the whitefly managed to swipe a plant gene is unclear. One risk, says Turlings, is {that a} virus served as an intermediate, shuttling genetic materials from a plant into the whitefly genome.
As researchers sequence extra genomes, it’s attainable that they’ll uncover extra examples of gene transfer between vegetation and animals, says Gloss.
“Insects taking the genes from the plants themselves is just that last bit of the arsenal that we hadn’t found yet,” he says. “In the battle between plants and their insect pests or pathogens, there are genes being drawn from all over the tree of life.”
