The Cloning And Functional Identification Of A RNA Virus Host Factor Gene TTOM1 From Tomato

It is known that host factors are required for viruses to replicate and/or maintain in the host cells. However, only a few host factors with clear in vivo function have been identified. By using PCR and 5' and 3' RACE, we were able to clone a homologue(named TTOM1) of Arabdopsis thaliania host factor gene, TOM1, which supports the replication of tobacco mosaic virus. The full-length cDNA of TTOM1, 1280 bp in length, encodes a deduced 288 a.a. protein with 7-pass explasmic domains. To identify the function of TTOM1 during the viral infection of the plant host, a 2.6 kb genomic DNA near the 5' end of TTOM1, was used to generate antisense TTOM1 transgenic tomato plants. Upon inoculation of cucumber mosaic virus (CMV), the symptom development in the transgenic plants was delayed, one week later than that of the non-transgenic control, and the symptom on the transgenic plants were much milder. Moreover, local lesion assay on Chenopodium amaranticole showed that the virus titer in the transgenic tomato plants were significantly lower than that of the non-transgenic plants. The collective results demonstrate that TTOM1 is a host factor involved in the replication and/or maintenance of CMV in tomato.