Complete nucleotide sequence and construction of an infectious clone of Chinese yam necrotic mosaic virus suggest that macluraviruses have the smallest genome among members of the family Potyviridae.

The complete nucleotide sequence of Chinese yam necrotic mosaic virus (CYNMV) was determined from cloned virus cDNA. The CYNMV genomic RNA is 8224 nucleotides in length, excluding the poly(A) tail, and contains one long open reading frame encoding a large polyprotein of 2620 amino acids. CYNMV has no counterpart to the P1 cistron and a short HC-Pro cistron located at the 5' side of the potyvirus genome. A full-length cDNA clone, pCYNMV, was assembled under the control of the cauliflower mosaic virus 35S promoter and the nopaline synthase terminator. Biolistic inoculation of Nagaimo plants with cDNA resulted in systemic necrotic mosaic symptoms typical of CYNMV infection. To our knowledge, this is the first report of the complete nucleotide sequence and construction of an infectious cDNA clone of a member of the genus Macluravirus.