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. 2023 Apr 10;24(7):811–822. doi: 10.1111/mpp.13330

FIGURE 1.

FIGURE 1

Schematic representations of foxtail mosaic virus (FoMV) and vectors that have been derived from it. (a) Wild‐type FoMV from left to right, the oval represents the 5′ 7‐methylguanosine cap structure, followed by a 5′ untranslated region (UTR), the RNA dependent RNA polymerase (RDRP), subgenomic promoter 1 (sgPro1) driving transcription of subgenomic RNA 1, the triple gene block proteins (TGB) 1, 2, and 3, a predicted open reading frame (ORF) 5A (5A) that is unnecessary for infection (Robertson et al., 2000), subgenomic promoter 2 (sgPro2) driving the transcription of subgenomic RNA 2, the coat protein (CP), a 3′ UTR that terminates at a polyA tail. (b) The FoMV FECT vector was developed as a virus overexpression (VOX) vector by replacing TGB1, 2, 3, and CP ORFs with a cloning site for foreign sequences expressed under control of sgPro1 (Liu & Kearney, 2010). The FoMV FECT vector consists of a 5′ UTR, RDRP, gene of interest (GOI) insertion site under control of sgPro1, and the 3′ UTR. (c) A virus‐induced gene silencing (VIGS) construct developed by Mei et al. (2016) by adding a multiple cloning site to the wild‐type FoMV genome immediately after the CP stop codon. Gene fragments are inserted at this location in the antisense orientation to induce silencing of endogenous plant genes. (d) FoMV VIGS vector developed by Liu et al. (2016) carries a duplicated sgPro2 (DP) that was inserted between TGB3 and the CP and preserves ORF 5A. Gene fragments are cloned as inverted repeats in the cloning site immediately following the DP. (e) The FoMV VOX vector (PV101) developed by Bouton et al. (2018) uses the duplicated sgPro2 promoter (DP) to drive expression of coding sequences inserted between TGB3 and CP. (f) Mei et al. (2019) developed and updated their FoMV vector to have the capacity for VIGS, VOX, and virus‐induced gene editing (VIGE). This version of FoMV is based on the Mei et al. (2016), and it includes a DP to drive expression of a GOI or produce functional single‐guide RNAs (gR) for CRISPR/Cas9 gene editing applications. All of the FoMV viral vector designs (b–f) are transcribed under the control of a 2× cauliflower mosaic virus 35S promoter (35S) and the nopaline synthase (NOS) terminator, and the grey arrows located along the genomes represent the positions of the sgPro1, sgPro2, and DPs.