Oaxacan Green Dent maize is not from Oaxaca

Oaxacan Green Dent is a maize (Zea mays L.) cultivar marketed as an introduced Mexican heritage cultivar adapted to the higher latitudes of the United States. Its adaptation and appearance contradict an origin in Oaxaca, Mexico, however, and no indigenous cultivars in Oaxaca are known to have the unique kernel colors of Oaxacan Green Dent. We compared phenotypes and genotypes of Oaxacan Green Dent sampled from three different sources along with several Corn Belt cultivars and 15 landrace accessions collected from a wide range of geography, altitude, and cultural groups in Oaxaca. Multivariate analysis of 13 phenotypic traits measured in a field experiment suggested that Oaxacan Green Dent is more closely related to Corn Belt Dents than to Oaxacan cultivars. Genomic analysis from DNA sequencing demonstrated unambiguously that Oaxacan Green Dents are even more distantly related to Oaxacan cultivars than typical US Corn Belt Dent cultivars are. Phenotypic, genetic, and historical data indicate that Oaxacan Green Dent is almost certainly directly derived from Ernest Strubbe's Green Dent cultivar, which he developed in Minnesota from crosses between a Corn Belt Dent cultivar and an intensely colored popcorn cultivar, with no contribution from Oaxacan cultivars.