Plasmid cDNA clones C1 Á23 , C2 T2BÁ23 and T3 Á163(A)Á23 were constructed through three steps: first, amplifying two fragments with appropriate primer pairs (see Supplementary Table 1 Figure 1 . Schematic representation of constructs used in this article. The constructs regulated from the 35S promoter and 35S terminator are indicated. The open reading frames encoding various cucumoviral proteins on the constructs are shown. The 23 nt of sequence identity between all genomic RNAs is indicated by a short thick bar. The tandem repeat of 163 nt is indicated by an arrow. The crosshatch lines represent the amino acid sequences different from the native sequence for either 2a or 2b. T3 Á163 (A)Á23 ; and finally, by ligating the two digested  fragments into the appropriate sites created by digestion  with the same enzymes. Plasmid cDNA clones C1 3081-3390 ,  C2 W2B2757-3065 ,  T3 Á163(A)Á141 ,  T3 1-2060 ,  T3 1-2223 ,  T3 1902-2386 and T3 2065-2386 were constructed via two  steps: first amplifying appropriate fragments, and then ligating these fragments into the pCass1 vector (43) . Plasmid cDNA clones C2 W2BC2a and T3 Á163(G) were constructed with a QuickChange Site-Directed Mutagenesis Kit (Stratagene) according to the manufacturer's instruction. All the amplified fragments as well as their joined regions in the plasmids were sequenced to ensure whether they were correct.