Cloning，Sequence Analysis and Expression in E ．coli of Coat Protein Gene and 3 Noncoding Region of Tom ato M osaic Virus

The coat protein (CP) gene and 3′noncoding region of tomato mosaic virus Sl isolate (ToMV Sl) were amplified by RT PCR with specific primers designed on the basis of reported ToMV L strain (ToMV L) sequence. The cDNA fragment was cloned and sequenced,its sequence showed that the CP gene has 480 nucleotides in length, which encodes 158 amino acids and 3′ noncoding region contains 202 nucleotides. The nucleotide sequence of ToMV Sl showed 99.5% homology when compared with that of ToMV L and 76.2% homology when compared with that of TMV Ul. The CP gene was inserted into pGEMEX 1, Western immuno blot showed that this gene was expressed in E.coli with the proper reading frame. The gene was also inserted into plant expression vector pBI121.