This invention relates in part to detecting herbicide tolerant plants-more specifically, an aad-1 transformation event in corn plants. The subject invention also provides assays for detecting the presence of the subject event in a sample (of corn grain, for example). Kits and conditions useful in conducting the assays are also provided. The subject invention also relates in part to plant breeding using the subject methods. In some embodiments, this event/polynucleotide sequence can be “stacked” with other traits. More specifically, the invention relates in part to an endpoint Taqman PCR assay for AAD-1 corn event 40278-9. Some embodiments are directed to assays that are capable of high throughput zygosity analysis. The subject invention further relates, in part, to the use of a preferred reference gene for use in determining zygosity.