The swede midge, Contarinia nasturtii, is a cecidomyiid fly that feeds specifically on plants within the Brassicaceae. Plants in this family employ a glucosinolate-myrosinase defense system, which can be highly toxic to non-specialist feeders. Feeding by C. nasturtii larvae induces gall formation, which can cause substantial yield losses thus making it a significant agricultural pest. A lack of genomic resources, in particular a reference genome, has limited deciphering the mechanisms underlying glucosinolate tolerance in C. nasturtii, which is of particular importance for managing this species. Here, we present an annotated, scaffolded reference genome of C. nasturtii using linked-read sequencing from a single individual and explore systems involved in glucosinolate detoxification. The C. nasturtii genome is similar in size and annotation completeness to that of the Hessian fly, Mayetiola destructor, but has greater contiguity. Several genes encoding enzymes involved in glucosinolate detoxification in other insect pests, including myrosinases, sulfatases, and glutathione S-transferases, were found, suggesting that C. nasturtii has developed similar strategies for feeding on Brassicaceae. The C. nasturtii genome will, therefore, be integral to continued research on plant-insect interactions in this system and contribute to effective pest management strategies.
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This work was supported by the Agriculture and Agri-Food Canada Genomic Resources and Development Initiative [grant J-001581 to B.A.M., M.A.E. and D.D.H.] and the NSERC-Industrial Research Chair Program [grant 545088 to B.A.M.].
The data underlying this article are available in GenBank at https://www.ncbi.nlm.nih.gov/ and can be accessed with PRJNA565389 and PRJNA579966. Data are also available in the USDA National Agricultural Library I5K workspace at https://i5k.nal.usda.gov/contarinia-nasturtii.
Mori, Boyd A.; Coutu, Cathy; Chen, Yolanda H.; Campbell, Erin O.; Dupuis, Julian R.; Erlandson, Martin A.; and Hegedus, Dwayne D., "De novo Whole Genome Assembly of the Swede Midge (Contarinia nasturtii), a Specialist of Brassicaceae, Using Linked-Read Sequencing" (2021). Entomology Faculty Publications. 211.