Abstract
The electroporation method was applied to introduce ordinary strain of tobacco mosaic virus (TMV-OM) RNA into free cells of Brassica campestris L. cv. Komatsuna, a natural non-host plant of TMV. The infection rate of the free cells was as low as 30% when a mixture of free cells and TMV-OM RNA was electroporated. However, the rate was enhanced to about 70% when the mixture was preincubated in an ice bath for 60min prior to electroporation, demonstrating that this virus could multiply in Komatsuna cells. On the other hand, fluorescent microscopy of thin sections of Komatsuna leaves inoculated with TMV-OM revealed that this virus could multiply in inoculated leaves without any visible symptoms but did not transfer to upper leaves. Considering the fact that cauliflower mosaic virus (CaMV) can infect with a higher rate in its host plant, Komatsuna, giving a typical symptom, it is likely that the degree of transfer and/or multiplication of TMV-OM in Komatsuna tissues might be much lower than that of CaMV in some reason, or that symptom appearance might be regulated by a different mechanism from that of viral multiplication.
