Findings of tobacco ringspot virus in ornamentals in the Netherlands from 1997 to 2020 indicate a need for evaluation of its EU-quarantine status

Abstract

Occasional findings of Tobacco ringspot virus (TRSV) in the Netherlands since 1997, were reason for large-scale surveys for TRSV in vegetatively propagated ornamental plants and for its vector, Xiphinema americanum sensu lato. In total, TRSV was identified in ten ornamental species, comprising over 30 cultivars, while X. americanum s.l. was not found. In addition, TRSV was identified in four ornamental species originating from outside the Netherlands. This report describes a newly designed and validated real time RT-PCR and gives an overview of TRSV findings and interceptions, including phylogenetic analyses of (nearly) complete genome sequences from available isolates and NCBI GenBank accessions in relation to their metadata of host and origin. Overall, the results suggest that TRSV entered the Netherlands on multiple occasions and was further spread by vegetative propagation. Furthermore, TRSV seems to be more widespread in the European Union (EU) than previously assumed, indicating that the current regulatory measures do not fully safeguard the absence of TRSV. Alternative strategies to protect the crops at risk are discussed, and reconsideration of the regulatory status of TRSV in the EU is recommended.