Cloning and sequence analysis of an infectious clone of Citrus yellow mosaic virus that can infect sweet orange via Agrobacterium-mediated inoculation

Abstract

Citrus yellow mosaic virus (CYMV), a member of the family Caulimoviridae, genus Badnavirus, causes citrus mosaic disease, a disease that occurs commonly in India. The CYMV genome has been cloned and its complete nucleotide sequence determined. Its DNA genome is 7559 bp in length and contains six putative open reading frames (ORFs), all on the plus-strand of the genome and each capable of encoding proteins with a molecular mass of greater than 10 kDa. ORF 3, the largest ORF, encodes a putative polyprotein for functions involved in virus movement, assembly and replication. The other ORFs encode proteins whose exact functions are not completely understood. The genome also contains a plant tRNAmet-binding site, which may serve as a primer for minus-strand DNA synthesis, in its intergenic region. Phylogenetic analysis of the badnaviruses revealed that CYMV is most closely related to Cacao swollen shoot virus. It was demonstrated that a construct containing 1·4 copies of the cloned CYMV genome could infect sweet orange via Agrobacterium-mediated inoculation.