-
[show abstract]
[hide abstract]
ABSTRACT: Because of its importance to the arthropod exoskeleton, chitin biogenesis is an attractive target for pest control. This point is demonstrated by the economically important benzoylurea compounds that are in wide use as highly specific agents to control insect populations. Nevertheless, the target sites of compounds that inhibit chitin biogenesis have remained elusive, likely preventing the full exploitation of the underlying mode of action in pest management. Here, we show that the acaricide etoxazole inhibits chitin biogenesis in Tetranychus urticae (the two-spotted spider mite), an economically important pest. We then developed a population-level bulk segregant mapping method, based on high-throughput genome sequencing, to identify a locus for monogenic, recessive resistance to etoxazole in a field-collected population. As supported by additional genetic studies, including sequencing across multiple resistant strains and genetic complementation tests, we associated a nonsynonymous mutation in the major T. urticae chitin synthase (CHS1) with resistance. The change is in a C-terminal transmembrane domain of CHS1 in a highly conserved region that may serve a noncatalytic but essential function. Our finding of a target-site resistance mutation in CHS1 shows that at least one highly specific chitin biosynthesis inhibitor acts directly to inhibit chitin synthase. Our work also raises the possibility that other chitin biogenesis inhibitors, such as the benzoylurea compounds, may also act by inhibition of chitin synthases. More generally, our genetic mapping approach should be powerful for high-resolution mapping of simple traits (resistance or otherwise) in arthropods.
Proceedings of the National Academy of Sciences 03/2012; 109(12):4407-12. · 9.68 Impact Factor
-
[show abstract]
[hide abstract]
ABSTRACT: Domestic pigeons are spectacularly diverse and exhibit variation in more traits than any other bird species [1]. In The Origin of Species, Charles Darwin repeatedly calls attention to the striking variation among domestic pigeon breeds-generated by thousands of years of artificial selection on a single species by human breeders-as a model for the process of natural divergence among wild populations and species [2]. Darwin proposed a morphology-based classification of domestic pigeon breeds [3], but the relationships among major groups of breeds and their geographic origins remain poorly understood [4, 5]. We used a large, geographically diverse sample of 361 individuals from 70 domestic pigeon breeds and two free-living populations to determine genetic relationships within this species. We found unexpected relationships among phenotypically divergent breeds as well as convergent evolution of derived traits among several breed groups. Our findings also illuminate the geographic origins of breed groups in India and the Middle East and suggest that racing breeds have made substantial contributions to feral pigeon populations.
Current biology: CB 02/2012; 22(4):302-8. · 10.99 Impact Factor
-
Xiangchao Gan,
Oliver Stegle,
Jonas Behr,
Joshua G Steffen,
Philipp Drewe,
Katie L Hildebrand,
Rune Lyngsoe,
Sebastian J Schultheiss, Edward J Osborne,
Vipin T Sreedharan, [......],
Paul Derwent,
Paul Kersey,
Eric J Belfield,
Nicholas P Harberd,
Eric Kemen,
Christopher Toomajian,
Paula X Kover,
Richard M Clark,
Gunnar Rätsch,
Richard Mott
[show abstract]
[hide abstract]
ABSTRACT: Genetic differences between Arabidopsis thaliana accessions underlie the plant's extensive phenotypic variation, and until now these have been interpreted largely in the context of the annotated reference accession Col-0. Here we report the sequencing, assembly and annotation of the genomes of 18 natural A. thaliana accessions, and their transcriptomes. When assessed on the basis of the reference annotation, one-third of protein-coding genes are predicted to be disrupted in at least one accession. However, re-annotation of each genome revealed that alternative gene models often restore coding potential. Gene expression in seedlings differed for nearly half of expressed genes and was frequently associated with cis variants within 5 kilobases, as were intron retention alternative splicing events. Sequence and expression variation is most pronounced in genes that respond to the biotic environment. Our data further promote evolutionary and functional studies in A. thaliana, especially the MAGIC genetic reference population descended from these accessions.
Nature 08/2011; 477(7365):419-23. · 36.28 Impact Factor
-
Xiangchao Gan,
Oliver Stegle,
Jonas Behr,
Joshua G. Steffen,
Philipp Drewe,
Katie L. Hildebrand,
Rune Lyngsoe,
Sebastian J. Schultheiss, Edward J. Osborne,
Vipin T. Sreedharan, [......],
Paul Derwent,
Paul Kersey,
Eric J. Belfield,
Nicholas P. Harberd,
Eric Kemen,
Christopher Toomajian,
Paula X. Kover,
Richard M. Clark,
Gunnar Rätsch,
Richard Mott
Nature 08/2011; 477(7365):419-423. · 36.28 Impact Factor
-
Miodrag Grbić,
Thomas Van Leeuwen,
Richard M Clark,
Stephane Rombauts,
Pierre Rouzé,
Vojislava Grbić, Edward J Osborne,
Wannes Dermauw,
Phuong Cao Thi Ngoc,
Félix Ortego, [......],
Kristof Demeestere,
Stefan R Henz,
T Ryan Gregory,
Johannes Mathieu,
Lou Verdon,
Laurent Farinelli,
Jeremy Schmutz,
Erika Lindquist,
René Feyereisen,
Yves Van de Peer
[show abstract]
[hide abstract]
ABSTRACT: The spider mite Tetranychus urticae is a cosmopolitan agricultural pest with an extensive host plant range and an extreme record of pesticide resistance. Here we present the completely sequenced and annotated spider mite genome, representing the first complete chelicerate genome. At 90 megabases T. urticae has the smallest sequenced arthropod genome. Compared with other arthropods, the spider mite genome shows unique changes in the hormonal environment and organization of the Hox complex, and also reveals evolutionary innovation of silk production. We find strong signatures of polyphagy and detoxification in gene families associated with feeding on different hosts and in new gene families acquired by lateral gene transfer. Deep transcriptome analysis of mites feeding on different plants shows how this pest responds to a changing host environment. The T. urticae genome thus offers new insights into arthropod evolution and plant-herbivore interactions, and provides unique opportunities for developing novel plant protection strategies.
Nature 01/2011; 479(7374):487-92. · 36.28 Impact Factor
