Resistance to pepper mild mottle tobamovirus conferred by the 54-kDa gene sequence in transgenic plants does not require expression of the wild-type 54-kDa protein.
We previously reported that Nicotiana benthamiana plants transformed with the wild-type 54-kDa region of the pepper mild mottle tobamovirus, S strain (PMMoV-S), displayed two different resistance responses against PMMoV infection. Some of the transgenic plants exhibited a complete and highly resistant phenotype while the remaining plants showed a delayed resistance (Tenllado et al., 1995, Virology 211, 170--183). Here we show that some of the N. benthamiana plants transformed with a construct expressing a PMMoV-S truncated 54-kDa protein coding sequence also displayed a complete and highly resistant phenotype similar to that shown by the wild-type 54-kDa transgenic plants. This result indicates that the wild-type, full-length 54-kDa protein is not required in mediating the complete resistance phenotype against PMMoV. The remaining truncated 54-kDa transgenic plants were susceptible to PMMoV infection but showed a variable delay in the appearance of symptoms. Unlike the wild-type 54-kDa transgenic plants, which were initially susceptible to the infection but recovered later, the truncated 54-kDa transgenic plants never exhibited this delayed resistance phenotype. However, they displayed a new type of altered symptomatic phenotype. The truncated 54-kDa transgenic lines also exhibited a lower level of transgenic transcripts compared to the wild-type 54-kDa transgenic lines which could account for the absence of the delayed resistance phenotype.
Tenllado
F
F
Departamento de Biología de Plantas, Centro de Investigaciones Biológicas, CSIC, Madrid, Spain.
García-Luque
I
I
Serra
M T
MT
Díaz-Ruíz
J R
JR
D015870:Gene Expression; D005814:Genes, Viral; D010935:Plant Diseases; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D012367:RNA, Viral / Q000378:metabolism; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics; D014026:Nicotiana / Q000821:virology; D017898:Tobamovirus / Q000235:genetics*
D012367:RNA, Viral; D012324:RNA-Dependent RNA Polymerase