Invasive Species Compendium

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Abstract

First report of Tobacco rattle virus and Cucumber mosaic virus in Phlox paniculata in France.

Abstract

P. paniculata (PP), a perennial plant from the family Polemoniaceae, is cultivated as an ornamental in gardens and for cut-flower production. In spring 2003, two types of symptoms were observed in PP plants grown for cut flowers on a farm in the Var department, France. Some plants showed a mild leaf mosaic, while others showed leaf browning and delayed growth. In plants showing mild mosaic, Cucumber mosaic virus (CMV) was detected on the basis of the symptoms exhibited by a range of inoculated plants, the observation of isometric particles (∼30 nm) with the electron microscope in crude sap preparations from the infected plants, and the positive reaction in double-antibody sandwich (DAS)-ELISA to polyclonal antibodies raised against CMV. In sap preparations from PP plants showing leaf browning symptoms, rod-shaped particles with 2 distinct sizes of 190-210 and 70-90 nm long, typical of those associated with tobraviruses, were revealed using electron microscopy. Local lesions typical of Tobacco rattle virus (TRV) were observed after inoculation of Nicotiana tabacum cv. Xanthi-nc, Chenopodium amaranticolor and C. quinoa. Total nucleic acid preparations were prepared from symptomatic plants, and amplicons of the expected size (463 bp) were generated by reverse-transcription (RT)-PCR using primers specific to TRV RNA 1. The nucleotide sequence of one amplicon was 93.6% identical to the sequence of a reference TRV isolate (GenBank Accession No. AJ586803). Twelve one-year-old PP plants were mechanically inoculated with an extract of infected tissues from one symptomatic PP plant. TRV was detected 2-6 months post inoculation in apical leaves of all inoculated plants by RT-PCR, although the plants did not express symptoms. Since no other pathogens were detected in the source plants, it is plausible that the lack of symptoms in back-inoculated plants is either due to a long incubation period or an interaction with particular environmental factors such as cold conditions. The survey of ∼200 plants revealed that ∼7, 10 and 1% were infected by TRV, CMV or by both viruses, respectively. CMV and TRV were previously detected in PP in Latvian SSR and in Lithuania. These results show that sanitary selection of PP prior to vegetative propagation should include a screening for TRV and CMV infections.