Table 1.
Strategies to engineer VIGS vectors for major crops.
| Family | Virus | Strategies to Design Vectors |
|---|---|---|
| Alphaflexiviridae | potato virus X [48] | Duplication of the subgenomic (sg) RNA promoter of the coat protein (CP) to flank a multiple cloning site between two CP sgRNA promoters |
| foxtail mosaic virus [54,55] | Insertion of the XbaI and XhoI sites immediately after the stop codon of the capsid protein gene [54] Or Duplication of CP subgenomic promoter to flank a multiple cloning site [55] |
|
| Betaflexiviridae | citrus leaf blotch virus [56] | Inserting a subgenomic RNA promoter followed by a PmlI site for inserting foreign sequences in the linear form or in the hairpin fashion |
| grapevine virus A [50] | Duplication of Movement Protein (MP) subgenomic RNA promoter to flank a multiple cloning site | |
| Bromoviridae | cucumber mosaic virus [57] | Replacing a portion at the 3′-end of ORF2b with a multiple cloning site in RNA-2 |
| prunus necrotic ringspot virus [58] | Inserting foreign sequences at the 3’end of the CP gene in RNA3; Combining RNA1 and RNA2 in the same binary vector to increase the efficiency | |
| brome mosaic virus [59] | Using the HindIII site in the RNA3 3′ untranslated region (UTR) for insertion; Replacing the BclI/BssHII flanked RNA3 intergenic region of the Festuca arundinacea strain with that from the Russian strain | |
| Caulimoviridae | rice tungro bacilliform virus [60] | Selectively keeping ORFIII and a 50 bp 3′-truncated ORF IV flanked by two constitutive promoters; adding a tRNA binding site essential for replication immediately after the first promoter near the 5′-end; adding a multiple cloning site immediately before the second promoter near the 3′end |
| Geminiviridae | tomato yellow leaf curl China virus [45] | Replacing the βC1 (pathogenic factor/VSR) ORF with a multiple cloning site in DNA β |
| african cassava mosaic virus [47] | Replacing a portion of the capsid protein (AV1) ORF with a multiple cloning site in DNA-A | |
| cotton leaf crumple virus [46] | Replacing the CP gene with a multiple cloning site in DNA-A | |
| Secoviridae | broad bean wilt virus [61] | Inserting a cloning site immediately after the stop codon of the RNA2 ORF in the 3′UTR of RNA2 |
| bean pod mottle virus [52] | Duplication of the protease site between MP and L-CP in RNA2 to flank a multiple cloning site | |
| tobacco ringspot virus [53] | Duplication of the C/A protease site between MP and CP in RNA2 to flank a multiple cloning site | |
| apple latent spherical virus [51] | Duplication of the Q/G protease site between 42KP and Vp25 in RNA2 to flank a multiple cloning site | |
| Tymoviridae | turnip yellow mosaic virus [62] | Inserting a cloning site immediately downstream the CP protein for inserting foreign sequence in the hairpin fashion; Duplicating the CP stop codon to keep the tRNA-like structure for infectivity |
| Virgaviridae | tobacco rattle virus [44] | Replacing non-structural genes in RNA2 with a multiple cloning site |
| pea early browning virus [63] | Replacing non-structural genes in RNA2 with a multiple cloning site | |
| barley stripe mosaic virus [64] | Inserting a multiple cloning site downstream of the γb (pathogenic factor/VSR) corresponding to the γ subgenomic RNA | |
| cucumber green mottle mosaic virus [49] | Duplication of the CP subgenomic RNA promoter to flank a BamHI site |