Submitted to: The Canadian Entomologist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/20/2005
Publication Date: 3/1/2006
Citation: Mittapalli, O., Shukle, R.H., Wise, I.L. 2006. Identification of mariner-like elements in Sitodiplosis mosellana (Diptera: Cecidomyiidae). Canadian Entomologist. 138(2):138-146. Interpretive Summary: The orange blossom wheat midge is the most important insect pest of wheat in western Canada and is an important pest of wheat in northern Europe, Russia and China. It is an emerging pest of wheat on the north-central plains of the United States with the potential of causing increased yield loss in wheat across the central plains of the United States. Alternate hosts of the pest include barley and rye. Larvae of the pest destroy the developing kernels in the wheat head. Additionally, damaged kernels can affect the baking quality of flour. To date, the only effective means of control of this pest has been insecticide applications. Recently, an effective gene for resistance has been characterized and is being incorporated into wheat cultivars in Canada. However, since only one gene for resistance has been identified there is concern about the development of biotypes of the pest capable of surviving on resistant wheat. We have identified a 'jumping gene' in the orange blossom wheat midge that is capable of moving from one position to another on the DNA of the pest. Knowledge about this jumping gene will help scientists develop molecular tools to manipulate genes in the pest as well as to locate genes on the DNA of the pest. Such jumping genes can also cause changes in the DNA of the pest that can lead to the evolution of virulent biotypes of the pest that can overcome formally resistant wheat. These studies will help scientists devise innovative methods for developing durable resistant wheat to prevent yield loss and the agricultural community will benefit from improved pest control that increases yield and quality without increasing costs.
Technical Abstract: Mariner-like element sequences were recovered from the genome of the orange blossom wheat midge, Sitodiplosis mosellana (Géhin), with degenerate PCR primers designed to conserved regions of mariner transposases. The deduced amino acid sequences for the mariner-like transposases from S. mosellana showed 67% to 78% identity with the peptide sequences of other mariner transposases. A phylogenetic analysis revealed the mariner-like elements from S. mosellana grouped in the mauritiana subfamily of mariner elements. Results from Southern gel blot analysis suggested mariner-like elements are at a moderate copy number in the genome of S. mosellana. Results have importance in selection of a transposon-based system for manipulation of the S. mosellana genome as well as in mapping genes and in possible genome re-modeling and development of virulent biotypes of the pest that can overcome resistant wheat.