Abstract:XC-1, a virus isolate, was identified in Nicotiana tabacum showing severe mosaic symptom in Xichang, Sichuan province of China, electron microscopy of the XC-1 revealed that it had flexuous filamentous particles with a diameter of 13 nm and length about 740-760 nm, N. tabacum NC89 inoculated with XC-1 developed vein clearing 5 days post-inoculation (dpi) and presented mosaic symptom 8-14 dpi. 3′terminal sequence of XC-1 was obtained by RT-PCR, XC-1 was clustered with other Wild tomato mosaic virus (WTMV) isolates in phylogenetic tree based on the CP gene sequence, and shared the highest identity (94.34%) with WTMV isolate from Guangdong by homologous alignment and cluster analysis, indicating that XC-1 was a WTMV isolate named WTMV-XC-1.