DNA-based species identification as a tool to distinguish invasive Nassella species in South Africa

Abstract

The three non-native Nassella species (N. neesiana, N. tenuissima, and N. trichotoma) occurring in the South African montane grasslands are morphologically cryptic, and hence difficult to distinguish from several taxonomically complex, co-occurring tufted C₃ perennial grass genera (e.g. Festuca), and amongst one another, especially when in a vegetative state. DNA-based species identification, as has been demonstrated with other plants, offers a possible solution. This study evaluated the use of single nucleotide polymorphisms to identify and differentiate between Nassella species. Two gene loci, petL–psaJ (petL) and ETS were used to discriminate the three Nassella species from each other, and from three native grass species (Aristida diffusa, Festuca caprina, and Koeleria capensis) and the non-native species Jarava plumosa. The result showed that the petL locus could only discriminate the different genera while EST locus could differentiate all the tested species. The cost of outsourcing the whole process to a genetic laboratory is reasonable, making DNA-based species identification a viable identification method for non-experts. With this tool, early detection of Nassella populations is now possible so that management can be implemented before the species spreads beyond control.