CONICET | Buscador de Institutos y Recursos Humanos

Imidazolinone resistance found in a sunflower wild population was successfullytransferred to a cultivated inbred line developing Imisun sunflowers. Genetic regulation of this trait has been reported to involve two genes: Imr1, an allelic variant of ahasl1 locus that codes for acetohydroxyacid synthase catalytic subunit, and the modifier Imr2 whose identity remains unknown but it could be related to non-target-site resistance such as xenobiotic metabolism. The aim of the present study was to characterize the gene expression of resistant and susceptible sunflower lines in response to imazethapyr herbicideby cDNA-AFLP. Three assays were carried out to determine: (i) optimal herbicidetreatment concentration (ii) duration of herbicide treatment (iii) in vitro acetohydroxyacid synthase activity to assess enzyme inhibition levels. An important number of genes related to metabolism of xenobiotics and stress was found: cytochrome P450 monooxygenases, UDP-glucuronosyl/UDP-lucosyltransferases, glycosyltransferases and ATP-binding cassette transporters, among others. These results suggest that non-target-site resistance mechanisms may contribute to herbicide resistance in Imisun sunflower and they could be related to the modifier gene Imr2. cDNA-AFLP allowed to detect candidate detoxificationrelated genes potentially involved in imidazolinone resistance in sunflower.