A simple screen to detect hybrids between native and introduced Phragmites australis in the United States and Canada

Abstract

In much of the United States and Canada, the common reed consists of both a native subspecies Phragmites australis americanus, and a highly invasive introduced subspecies P. australis australis. DNA testing is generally used to distinguish them definitively and is necessary to detect hybridization. We report a group of single nucleotide polymorphisms and indels in the nuclear NRT2 gene of Phragmites that differentiate North American native and European-introduced populations. All native samples tested were identical in NRT2 sequence over 1564 bases except for two positions. There were nine positions, consisting of seven base substitutions and two indels, at which all introduced samples were fixed for a different allele than the native samples. For the two indels, samples collected from northern Europe were also fixed for the same allele as the introduced samples collected across North America. One of the indels was easily detected by a PCR-RFLP assay and provides a rapid and inexpensive way to screen for hybrids between native and European-introduced populations of Phragmites and thus can facilitate more widespread surveillance for hybrids between native and introduced populations in North America.