Cymbidium mosaic virus coat protein gene in antisense confers resistance to transgenic Nicotiana occidentalis

The nucleotide sequence of the 3'-terminal region of the Korean isolate of cymbidium mosaic virus (CyMV-Ca) from a naturally infected cattleya was determined. The sequence contains an open reading frame (ORF) coding for the viral coat protein (CP) at the 3'-end and three other ORFs (triple gene block or movement protein) of CyMV. The CP gene encodes a polypeptide chain of 220 amino acids with a molecular mass of 23,760 Da. The deduced CP sequence showed a strong homology with those of two CyMVs reported. A construct of the CyMV-Ca CP gene in the antisense orientation in the plant expression vector pMBP1 was transferred via Agrobacterium tumefaciens-mediated transformation into Nicotiana occidentalis which is a propagation host of CyMV. The T1 progeny of the transgenic plants were inoculated with CyMV and found to be highly resistant to CyMV infection.