Tetranychus urticae (Two-spotted spider mite) Assembly and Gene Annotation

About Tetranychus urticae

Tetranychus urticae, the two-spotted spider mite, is a tiny (~0.4mm long) herbivorous chelicerate that eats a wide range of plants, including many agriculturally important species such as maize and tomato. T. urticae has adaptations to cope with plant defence strategies, and is able to rapidly develop resistance to pesticides [1], so infestations are often controlled with predatory mites such as Phytoseiulus persimilis.

In common with the pea aphid, T. urticae can synthesize carotenoids (unlike all other animals) due to fungal-like genes gained through horizontal gene transfer [2]. These carotenoid genes are not known in other arthropods, but appear sufficiently similar to imply one ancestral transfer event in arthropods, suggesting a secondary transfer between aphid and spider mite (since gene loss in so many other species is implausible) [3]. As their name suggests, spider mites spin webs with silk on the undersides of leaves, although the mechanism has a distinct evolutionary origin compared to silk production in spiders. The genome sequence of T. urticae is thus a valuable resource for the study of specific areas such as pest-plant interactions or the use of silk as a biomaterial, and as a representative chelicerate in broader studies of metazoa [3].

Picture credit (Creative Commons BY-SA 3.0): J. Holopainen 2006

Assembly

The Tetranychus urticae genome (London strain) was Sanger-sequenced to 8.05x coverage, using embryos to avoid plant and microbial contamination. The assembly consists of 640 scaffolds, with a genome size of approximately 90 Mb, representing a relatively small genome for a chelicerate (or, indeed, any metazoan).

Annotation

The protein-coding and RNA genes displayed in Ensembl Genomes are imported from the ORCAE [4] gene set released in October 2015.

References

1. Acaricide resistance mechanisms in the two-spotted spider mite Tetranychus urticae and other important Acari: a review.
   Van Leeuwen T, Vontas J, Tsagkarakou A, Dermauw W, Tirry L. 2010. Insect Biochemistry and Molecular Biology. 40:563-572.
2. Horizontally transferred fungal carotenoid genes in the two-spotted spider mite Tetranychus urticae.
   Altincicek B, Kovacs JL, Gerardo NM. 2012. Biology Letters. 8:253-257.
3. The genome of Tetranychus urticae reveals herbivorous pest adaptations.
   Grbi M, Van Leeuwen T, Clark RM, Rombauts S, Rouz P, Grbi V, Osborne EJ, Dermauw W, Ngoc PC, Ortego F et al. 2011. Nature. 479:487-492.
4. ORCAE: online resource for community annotation of eukaryotes.
   Sterck L, Billiau K, Abeel T, Rouz P, Van de Peer Y. 2012. Nature Methods. 9:1041.

More information

General information about this species can be found in Wikipedia.