Abstract

The understanding of mechanism of herbicide resistance in weeds is essential for adequate or innovative weed management practices. The aim of this study was to identify and analyze the expression of genes related to degradation enhancement of imazethapyr in barnyardgrass (Echinochloa crus-galli L. Beauv.). One susceptible (SUSSP01) and two populations previouslly identified as resistant to imazethapyr (ARRGR01 and PALMS01) were used. Gene expression of CYP and GST, the translation initiating factor eIF4B, and ALS genes were evaluated after imazethapyr spraying. A reference gene stability analysis was carried out, wherein the genes 18S and actin showed to be more stable in response to the population and herbicide treatment. The gene expression analysis was performed by qRT-PCR. There was no difference in the relative expression of the ALS gene. The CYP81A6 and GSTF1 genes showed higher relative expression in the resistant populations. The CYP81A6 gene had expression 9.61 and 8.44 higher in the resistant populations ARRGR01 and PALMS01, respectively, in comparison with the untreated susceptible population. The expression of this gene was induced by spraying the herbicide imazethapyr. The GSTF1 gene showed higher relative expression in PALMS01 population, reaching 12.30 times higher in plants treated with imazethapyr in relation to untreated susceptible population. The expression of eIF4B gene in the resistant populations treated with imazethapyr was about six times higher than observed in susceptible population. The high relative expression of CYP81A6 and GSTF1 genes indicate the importance of degradation enhancement for the resistance of barnyargrass to imazethapyr.

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