Whitefly Hijacks a Plant Detoxification Gene That Neutralizes Plant Toxins with no help from Darwin

Article: Whitefly Hijacks a Plant Detoxification Gene That Neutralizes Plant Toxins

Introduction

Plants have developed a vast array of defense mechanisms to protect themselves from herbivores, including the production of toxic secondary metabolites. One such group of secondary metabolites is phenolic glucosides, which are found in a wide variety of plants. However, many herbivores have developed resistance to these toxins, enabling them to feed on these plants without harm.

The whitefly, Bemisia tabaci, is a cosmopolitan agricultural pest that is known for its ability to vector several plant pathogenic viruses. Whiteflies are also highly polyphagous, meaning that they can feed on a wide variety of plant species. One of the mechanisms that contributes to the whitefly's success is its ability to detoxify phenolic glucosides.

A recent study published in the journal Cell has shown that whiteflies have acquired a plant-derived phenolic glucoside malonyltransferase gene, BtPMaT1, through horizontal gene transfer (HGT). This gene enables whiteflies to neutralize phenolic glucosides, allowing them to feed on a wider range of plants and tolerate higher levels of these toxins.

Horizontal Gene Transfer

HGT is the movement of genetic material between organisms that are not in a parent-offspring relationship. HGT can occur between different species of bacteria, as well as between bacteria and eukaryotes. In the case of the whitefly, HGT is thought to have occurred between the whitefly and a plant that it feeds on.

HGT is a relatively rare event, but it can have significant consequences. In the case of the whitefly, HGT has provided the insect with a powerful new tool for overcoming plant defenses.

BtPMaT1 and Phenolic Glucoside Detoxification

BtPMaT1 encodes an enzyme that catalyzes the malonylation of phenolic glucosides. Malonylation is a modification that can increase the hydrophobicity of a molecule, making it more soluble in lipids. This can facilitate the transport of phenolic glucosides across cellular membranes, allowing them to be detoxified.

The study by Zhang et al. (2021) showed that whiteflies that express BtPMaT1 are more resistant to phenolic glucosides than whiteflies that do not express the gene. This suggests that BtPMaT1 plays a key role in the whitefly's ability to detoxify these toxins.

Implications for Pest Control

The discovery that whiteflies have acquired BtPMaT1 through HGT has several implications for pest control. First, it suggests that new pest control strategies could be developed by targeting BtPMaT1. For example, it may be possible to develop pesticides that specifically inhibit BtPMaT1, or to engineer plants that produce small interfering RNAs (siRNAs) that silence the BtPMaT1 gene.

Second, the study provides a new example of how HGT can shape plant-insect interactions. HGT is a relatively rare event, but it can have significant consequences. In the case of the whitefly, HGT has provided the insect with a powerful new tool for overcoming plant defenses.

Conclusion

The study by Zhang et al. (2021) is a significant advance in our understanding of how herbivores overcome plant defenses. The discovery that whiteflies have acquired a plant-derived gene through HGT is a fascinating example of the arms race between plants and their insect predators. This study also has potential implications for the development of new pest control strategies.

Concepts in this article Challenges Neo Darwinism.

Neo Darwinism holds that new traits arise through random mutations in genes. However, the acquisition of CYP6BG1 by whiteflies is an example of horizontal gene transfer, in which a gene is transferred from one organism to another without the need for mutation.

The acquisition of CYP6BG1 is not the first example of horizontal gene transfer in whiteflies. Previous studies have shown that whiteflies have acquired genes from bacteria and fungi. These genes have given whiteflies the ability to resist insecticides, tolerate herbicides, and synthesize essential nutrients.

The ability of whiteflies to acquire genes from other organisms is a major reason why they have been so successful at adapting to new environments and overcoming human attempts to control them.

Further implications for Neo Darwinism

The discovery of horizontal gene transfer in whiteflies has several implications for neo darwinism. First, it suggests that new traits can arise through the acquisition of genes from other organisms without NeoDarwinian random mutations. This means that the process of evolution is more complex and nuanced than previously thought.

Second, the acquisition of CYP6BG1 by whiteflies is an example of convergent evolution, in which two organisms independently evolve the same trait. This suggests that convergent evolution may be more common than previously thought, and that it may play a role in the evolution of complex traits.

Third, the ability of whiteflies to acquire genes from other organisms makes them more difficult to control. This is because genes for pesticide resistance, herbicide tolerance, and other traits can be quickly transferred from one whitefly population to another.

Conclusion

The discovery of horizontal gene transfer in whiteflies is a significant advance in our understanding of evolution. It challenges the basic tenets of neo darwinism and suggests that the process of evolution is more complex than previously thought. This discovery also has important implications for agriculture, as it highlights the need for new approaches to pest control.