Whole Genome Sequencing of Tetranychus urticae: novel genomic tools in Acarological research

National audienceGenetic model systems, such as C. elegans, fruitfly, zebrafish and mouse have rapidly advanced our understanding of genetics, development, population biology and evolution. These species became model organisms in part because of several common characteristics: rapid development, relatively small genomes and easy laboratory maintenance. To date, the development of a chelicerate model system has been hampered by their complex ontogeny, long development time and large genomes. Thus, a challenge for the future progress for many aspects of chelicerate biology is the development of a model organism for this group. Toward this end, we are developing a chelicerate genetic model: the two spotted spider mite Tetranychus urticae. As representatives of this basal taxon of arthropods, spider mites are of special importance to several areas of science including phylogenetics, developmental biology, evolution, ecology and genomics. In addition, spider mites are major agricultural pests and are therefore of substantial economic importance and significance for the biotechnology of pest control and energy conservation. T. urticae has one of the smallest genomes in arthropods determined so far (75 Mbp, 60% of the size of the Drosophila genome), undergoes rapid development and is easy to maintain in the lab. These features make T. urticae an excellent candidate for developing into a chelicerate model The whole genome sequencing project currently underway (USA Department of Energy, Joint Genome Institute http://www.jgi.doe.gov/sequencing/why/CSP2007/spidermite.html) will produce 8X sequence] coverage of the genome of T. urticae London strain and 1X sequence]coverage of the Montpellier strain. In addition to whole genome sequencing JGI will perform 75,000 EST sequences to aid in genome annotation. The whole genome sequence of T. urticae will be annotated, defining the total gene number and regulatory and transcribed regions. Final annotation of transcribed regions will be used for the design of a spider mite whole genome expression microarray. Together with already developed protocols for antibody and in situ detection of proteins and RNA distribution and RNAi reverse genetic gene silencing these new tools will open new perspectives and approaches in acarology ranging from comparative and functional genomics to genetics, population biology, plant herbivore interaction