Virus infections reduce in vitro multiplication of 'Malling Landmark' raspberry

Virus-infected plants are often symptomless and may be inadvertently used a s explant sources in tissue culture research. Our objective was to determin e the effect of virus infection on micropropagation. We studied the effects of single and multiple infections of three common raspberry viruses on the in vitro culture of 'Malling Landmark' red raspberry (Rubus idaeus L.). Vi rus-infected raspberry plants were produced by leaf-graft inoculation from known-infected plants onto virus-free 'Malling Landmark'. Single-virus sour ce plants were infected with either tobacco streak ilarvirus (TSV), tomato ringspot nepovirus (TomRSV), or raspberry bushy dwarf idaeovirus (RBDV) and were free of other viruses as determined by enzyme-linked immunosorbent as say (ELISA) and bioassay. Virus-free, single, and multiple virus-infected ' Malling Landmark' explants were initiated into culture and multiplied on An derson's medium with 8.9 mu M N-6-benzyladenine (BA). At the end of the mul tiplication tests, ELISA reconfirmed virus infections. In vitro multiplicat ion of 'Malling Landmark' was significantly reduced by multiple infections, and multiplication of plants infected with all three viruses (RBDV + TomRS V + TSV) was less than half that of virus-free cultures. Shoot height and m orphology of in vitro cultures were not influenced by virus infection. The greenhouse stock plant with the three-virus infection was stunted and yello w compared to the control and the other infected plants.