Herbicide Resistance Screening Assay

Herbicide resistance screening is a method that can be used not only to determine presence of the enzyme, phosphinothricin acetyltransferase, encoded by either the
Bar
or the
Pat
gene in transgenic maize, but also to assess the inheritance ratio of those genes in a segregating population. Herbicide screening can also be used to study linkage of a transgene of interest that was cotransformed with the herbicide resistance marker gene.By combining the herbicide screen assay with a
PCR
-based screen of leaf tissue
DNA
for the presence of both the
Bar
or the
Pat
gene marker and a cotransformed transgene of interest from the same seedling tissue and maintaining that seedling identity, the researcher can identify linkage or the possible breakdown in linkage of the marker gene and the transgene of interest. Further, the occurrence of “DNA silencing” can be evaluated if an individual seedling that was susceptible to the applied herbicide nonetheless gave PCR data that indicated presence of the gene responsible for herbicide resistance. Similarly, “DNA silencing” of the gene of interest may be investigated if the seeds can be screened and scored for that phenotypic trait in a nondestructive manner prior to planting.