Isolation of mutants of Arabidopsis thaliana in which accumulation of tobacco mosaic virus coat protein is reduced to low levels.

We have found that Arabidopsis thaliana is susceptible to infection with a crucifer strain of tobacco mosaic virus (TMV-Cg); the coat protein of TMV-Cg accumulated to a high level in uninoculated rosette leaves several days after inoculation. As a first step in the search for host-coded factors that are involved in virus multiplication, we isolated mutants of A. thaliana in which the accumulation of TMV-Cg coat protein was reduced to low levels. Of 6000 M2 plants descended from ethyl methanesulfonate-treated seeds, two such lines (PD114 and PD378) were isolated. Genetic analyses suggested that the PD114 phenotype was caused by a single nuclear recessive mutation, and that PD114 and PD378 belonged to the same complementation group. The coat protein accumulation of a tomato strain of TMV (TMV-L) was also reduced in PD114 plants compared to that in the wild-type plants. In contrast, PD114 plants infected with turnip crinkle or turnip yellow mosaic viruses, which belong to taxonomic groups other than Tobamovirus, expressed similar levels of these coat proteins as did infected wild-type plants.