Institute for Biodiversity and Ecosystem Dynamics

PhD Defence ceremony Wim Jonckheere

12Jan2018 11:00


On Friday January 12, Wim Jonckheere will defend his PhD thesis

Thesis cover Wim Jonckheere

The salivary proteome of Tetranychus urticae: key to its polyphagous nature?

The herbivorous spider mite Tetranychus urticae (Acari: Tetranychidae) is notorious for having an extremely large host plant range. Being this polyphagous is exceptional since plants possess various defensive mechanisms, including the production of toxins. Herbivores need to be able to deal with these defenses in order to thrive on a specific plant. This requires adaptation, often leading to specialization. Nevertheless, T. urticae, as a species, has been recorded on plants belonging to more than 140 families, and must therefore have evolved a variety of mechanisms allowing it to cope with a diverse arsenal of plant defenses.

In arthropod herbivores, the saliva has been proposed as an important mediator of digestion, detoxification and defense suppression. In this PhD thesis, the composition of spider mite saliva was investigated using a multidisciplinary approach based on in silico prediction and proteomics analysis of secreted saliva, combined with proterosomal expression analysis and confirmation of the salivary origin using whole-mount in situ hybridization. A list of almost one hundred T. urticae salivary proteins is presented, which will provide the foundation for a more detailed understanding of the mite-plant interaction at the molecular level. Some salivary proteins were shown to act as “effectors”, manipulating the host defense response. An OrthoMCL analysis further shed some light on the salivary proteome of the related specialists T. evansi and T. lintearius. Finally, a new spider mite-specific salivary protein family (denominated the SHOT family) is identified, showing a clear link with specialization to certain host plants. It is concluded that the salivary protein complement of T. urticae is key to its polyphagous nature.

Published by  IBED