The hidden diversity of the potato cyst nematode Globodera pallida in the south of Peru

Abstract

Our knowledge of the diversity of potato cyst nematodes in their native areas still remains patchy and should be improved. A previous study based on 42 Peruvian Globodera pallida populations revealed a clear south to north phylogeographic pattern, with five well-supported clades and maximum diversity observed in the south of Peru. In order to investigate this phylogeographic pattern more closely, we genotyped a larger collection of Peruvian populations using both cathepsin L gene sequence data and a new set of 13 microsatellite loci. Using different genetic analyses (STRUCTURE, DAPC), we consistently obtained the same results that led to similar conclusions: the presence of a larger genetic diversity than previously known suggesting the presence of cryptic species in the south of Peru. These investigations also allowed us to clarify the geographic borders of the previously described G. pallida genetic clades and to update our knowledge of the genetic structure of this species in its native area, with the presence of additional clades. A distance-based redundancy analysis (dbRDA) was also carried to understand whether there was a correlation between the population genetic differentiation and environmental conditions. This analysis showed that genetic distances observed between G. pallida populations are explained firstly by geographic distances, but also by climatic and soil conditions. This work could lead to a revision of the taxonomy that may have strong implications for risk assessment and management, especially on a quarantine species.