A recent study has described how a whitefly uses a stolen plant gene to elude its host’s defences – representing the first known example of a natural gene transfer from a plant to an insect.
Overcoming host defences
With over 400 million years of co-evolution with insect herbivores, plants have developed extremely diverse morphological, molecular and biochemical defences to withstand insect attacks. Among the biochemical defences, plant secondary metabolites are the most diverse and effective. The most abundant secondary metabolites are phenolic glycosides which strongly affect growth, development and behaviour of insects. Nonetheless, generalist insects can overcome these effects – mechanisms of which remain largely unknown.
The sweet potato whitefly, Bemisia tabaci, is a species complex of at least 30 cryptic species. It is a pest that can seriously reduce crop yields and can also feed on various kinds of food. Most of its host plants contain phenolic glycosides, making it an excellent model to identify the molecular mechanisms involved in overcoming plant defences.
First known gene transfer
In this study, published in Cell, researchers used bioinformatic, molecular and biochemical approaches to show that the B. tabaci genome harbours a plant-specific and horizontally transferred gene. This gene, specifically known as BtPMaT1, encodes a phenolic glucoside malonyltransferase that enables the detoxification of phenolic glycosides. The team carried out analyses to show that the gene was integrated into the whitefly genome, rather than being from contaminated plant DNA samples.
This discovery reveals an unexpected route by which the whitefly has evolved the ability to overcome the defences of its host plants. The team also showed, using small interfering RNAs, that silencing BtPMaT1 is a highly effective way to impair the whiteflies’ detoxification ability and control this global pest.
The team believe that as researchers sequence more genomes, it is likely that more examples of gene transfer between plants and animals will be found.
Image credit: By ajcespedes – canva.com