Weed-herbicide-resistance is a worldwide problem impacting crop-yields.  Herbicide-resistance due to enhanced-herbicide-metabolism (EMR) in weeds is not genetically well characterized.  An RNA-Seq transcriptome analysis was used to identify genes conferring EMR in a population (R) of a major global weed (Lolium rigidum), in which herbicide-resistance to diclofop-methyl was experimentally evolved through recurrent selection from a susceptible (S) progenitor population.  A reference transcriptome of 19,623 contigs was assembled (454 sequencing). Transcriptomic-level gene-expression was measured using Illumina 100 bp reads. In a forward genetics validation experiment, nine contigs, found overexpressed in R vs S plants, co-segregated with the resistance phenotype in an F2 population, including 3 CytP450, 3 GST, and 1 GT. In a physiological validation experiment where 2, 4-D induced diclofop-methyl protection in S individuals due to increased metabolism, seven of the nine genetically-validated contigs were significantly induced. Finally 4 of these genes were found over-expressed in resistant populations collected in fields.

Genomic approach to reveal non-target-site herbicide resistance mechanisms

248th National Meeting (2014)

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