When you think of the mite, you wouldn't think that its genome would be complex or dynamic. Now, though, researchers have taken a closer look at the remarkable features inherent in an arthropod that's widely employed to control plant pests.
Mites are natural enemies of several agricultural pests. This means that they are shipped throughout the world to fruit growers. The mite, Metaseiulus occidentalis, is used by many farmers to control spider mites, which feed on and destroy fruits.
"I have been studying the behavior, ecology, and molecular biology of these mites for more than 40 years," said Marjorie Hoy, lead author from the University of Florida. "So I was very keen to sequence the entire genome to reveal the full catalogue of genes."
In this latest study, the researchers focused their attention on genes that are involved in processes linked to paralysis and pre-oral digestion of prey species. They also looked at the parahaploid sex determination system, and how the mite senses chemical cues from its surroundings and defends itself from infections.
So what did they find? It turns out that the mite had a lot more intron gains and losses than other insects. This makes the evolutionary history of the mite far more complex than usually expected.
"The dynamic gains and losses of introns in the genes of this mite are in stark contrast to its closest relative with a draft genome assembly, the Ixodes tick," said Robert Waterhouse, lead author of the new study from the University of Geneva.
The researchers actually found that the tick had five copies of Dicer-2, which is a gene found almost exclusively in single-copy in other arthropods. This in particular suggests that there may be a possible rewiring of RNA processing pathways.
"These resources greatly improve the genomic sampling of chelicerates, a group of arthropods that has so far been poorly represented mainly due to challenges associated with their often very large genomes," said Stephen Richards from the Baylor College of Medicine.
The findings, published in the journal Genome Biology and Evolution, could help researchers better understand the relationships among groups of arthropods, and also allows researchers to conduct better analyses on predatory mites in addition to other arachnids.
